Repaired the broken benchmarks project (#677)

Removed `SortService.CheckIfProcessed()`, which was supposed to disallow multiple sort parameters. But it never worked. For example, if you pass `http://host/path?sort=a&sort=b`, it gets translated by `Microsoft.AspNetCore.Http.QueryCollection` into value "a,b". The check prevented to run benchmarks multiple times.

Also reactivated the build flag on all combinations of Platform/Configuration in Solution Configuration Manager for all projects.

Removed some benchmarks, for which no equivalent code exists anymore. But kept the benchmark on namespace-from-path extraction (and optimized a bit), because it nicely shows the perf difference between using strings and `ReadOnlySpan<char>`.

Also deleted old output markdown files from source control, as they differ per machine.

Finally, the stats from my laptop:

|                  Method |     Mean |     Error |    StdDev |
|------------------------ |---------:|----------:|----------:|
| DeserializeSimpleObject | 7.684 us | 0.0692 us | 0.0578 us |

|                Method |     Mean |     Error |    StdDev |
|---------------------- |---------:|----------:|----------:|
| SerializeSimpleObject | 7.871 us | 0.1011 us | 0.0946 us |

|         Method |         Mean |      Error |     StdDev |       Median |     Gen 0 |    Gen 1 | Gen 2 |  Allocated |
|--------------- |-------------:|-----------:|-----------:|-------------:|----------:|---------:|------:|-----------:|
|  AscendingSort |     2.680 us |  0.0211 us |  0.0449 us |     2.663 us |    1.0185 |   0.0076 |     - |     4.7 KB |
| DescendingSort |     2.728 us |  0.0258 us |  0.0527 us |     2.739 us |    1.0262 |   0.0076 |     - |    4.73 KB |
|   ComplexQuery | 3,258.409 us | 25.9838 us | 54.8087 us | 3,230.178 us | 1148.4375 | 281.2500 |     - | 5308.28 KB |

|            Method |      Mean |    Error |   StdDev |    Median |  Gen 0 | Gen 1 | Gen 2 | Allocated |
|------------------ |----------:|---------:|---------:|----------:|-------:|------:|------:|----------:|
|  UsingStringSplit | 244.66 ns | 0.783 ns | 1.702 ns | 244.60 ns | 0.1493 |     - |     - |     704 B |
| UsingReadOnlySpan |  69.72 ns | 2.638 ns | 5.680 ns |  66.09 ns | 0.0288 |     - |     - |     136 B |

Author: Bart Koelman

JsonApiDotnetCore.sln

@@ -41,7 +41,7 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "JsonApiDotNetCore", "src\Js
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "GettingStarted", "src\Examples\GettingStarted\GettingStarted.csproj", "{067FFD7A-C66B-473D-8471-37F5C95DF61C}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "IntegrationTests", "test\IntegrationTests\IntegrationTests.csproj", "{CEB08B86-6BF1-4227-B20F-45AE9C1CC6D9}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "IntegrationTests", "test\IntegrationTests\IntegrationTests.csproj", "{CEB08B86-6BF1-4227-B20F-45AE9C1CC6D9}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -56,11 +56,15 @@ Global
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|x64.Build.0 = Debug|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Debug|x86.Build.0 = Debug|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|Any CPU.Build.0 = Release|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|x64.ActiveCfg = Release|Any CPU
+		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|x64.Build.0 = Release|Any CPU
 		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|x86.ActiveCfg = Release|Any CPU
+		{CAF331F8-9255-4D72-A1A8-A54141E99F1E}.Release|x86.Build.0 = Release|Any CPU
 		{4F15A8F8-5BC6-45A1-BC51-03F921B726A4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{4F15A8F8-5BC6-45A1-BC51-03F921B726A4}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{4F15A8F8-5BC6-45A1-BC51-03F921B726A4}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -98,6 +102,7 @@ Global
 		{03032A2F-664D-4DD8-A82F-AD8A482EDD85}.Release|x86.ActiveCfg = Release|Any CPU
 		{03032A2F-664D-4DD8-A82F-AD8A482EDD85}.Release|x86.Build.0 = Release|Any CPU
 		{DF0FCFB2-CB12-44BA-BBB5-1BE0BCFCD14C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DF0FCFB2-CB12-44BA-BBB5-1BE0BCFCD14C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{DF0FCFB2-CB12-44BA-BBB5-1BE0BCFCD14C}.Debug|x64.ActiveCfg = Debug|Any CPU
 		{DF0FCFB2-CB12-44BA-BBB5-1BE0BCFCD14C}.Debug|x64.Build.0 = Debug|Any CPU
 		{DF0FCFB2-CB12-44BA-BBB5-1BE0BCFCD14C}.Debug|x86.ActiveCfg = Debug|Any CPU
@@ -111,11 +116,15 @@ Global
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|x64.Build.0 = Debug|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Debug|x86.Build.0 = Debug|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|Any CPU.Build.0 = Release|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|x64.ActiveCfg = Release|Any CPU
+		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|x64.Build.0 = Release|Any CPU
 		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|x86.ActiveCfg = Release|Any CPU
+		{C916EBDA-3429-4FEA-AFB3-DF7CA32A8C6A}.Release|x86.Build.0 = Release|Any CPU
 		{789085E1-048F-4996-B600-791B9CA3A663}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{789085E1-048F-4996-B600-791B9CA3A663}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{789085E1-048F-4996-B600-791B9CA3A663}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -143,11 +152,15 @@ Global
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|x64.Build.0 = Debug|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Debug|x86.Build.0 = Debug|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|Any CPU.Build.0 = Release|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|x64.ActiveCfg = Release|Any CPU
+		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|x64.Build.0 = Release|Any CPU
 		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|x86.ActiveCfg = Release|Any CPU
+		{21D27239-138D-4604-8E49-DCBE41BCE4C8}.Release|x86.Build.0 = Release|Any CPU
 		{067FFD7A-C66B-473D-8471-37F5C95DF61C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{067FFD7A-C66B-473D-8471-37F5C95DF61C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{067FFD7A-C66B-473D-8471-37F5C95DF61C}.Debug|x64.ActiveCfg = Debug|Any CPU