C++/C#: Move the Windows autobuilder into a subfolder in ql/csharp.

This is a necessary preparation for moving the C# dependency management to `paket`,
which in turn is a necessary preparation for moving the C# build to bazel.

As we discovered in #16376,
`paket` tries to restore all projects recursively from the root folder.
If we support building C# code under both `ql/csharp` and `ql/cpp`, we need
to have a single lockfile under `ql`, as both codebases share the same set of dependencies
(and utilities from `ql/csharp/extractor`).
Then, `paket` will also try to restore things that look like "C# projects" in other languages'
folders, which is not what we want.
Therefore, we address this by moving all C# code into a common root directory, `ql/csharp`.

This needs an internal PR to adjust the buildsystem to look for the autobuilder in the new location.

Author: criemen

.github/workflows/csharp-qltest.yml

@@ -84,7 +84,7 @@ jobs:
           dotnet test -p:RuntimeFrameworkVersion=8.0.1 extractor/Semmle.Util.Tests
           dotnet test -p:RuntimeFrameworkVersion=8.0.1 extractor/Semmle.Extraction.Tests
           dotnet test -p:RuntimeFrameworkVersion=8.0.1 autobuilder/Semmle.Autobuild.CSharp.Tests
-          dotnet test -p:RuntimeFrameworkVersion=8.0.1 "${{ github.workspace }}/cpp/autobuilder/Semmle.Autobuild.Cpp.Tests"
+          dotnet test -p:RuntimeFrameworkVersion=8.0.1 "${{ github.workspace }}/csharp/autobuilder/Semmle.Autobuild.Cpp.Tests"
         shell: bash
   stubgentest:
     runs-on: ubuntu-latest

CODEOWNERS

@@ -1,6 +1,8 @@
 /cpp/ @github/codeql-c-analysis
 /cpp/autobuilder/ @github/codeql-c-extractor
 /csharp/ @github/codeql-csharp
+/csharp/autobuilder/Semmle.Autobuild.Cpp @github/codeql-c-extractor
+/csharp/autobuilder/Semmle.Autobuild.Cpp.Tests @github/codeql-c-extractor
 /go/ @github/codeql-go
 /java/ @github/codeql-java
 /javascript/ @github/codeql-javascript

cpp/autobuilder/.gitignore

@@ -0,0 +1 @@
+The Windows autobuilder that used to live in this directory moved to `csharp/autobuilder/Semmle.Autobuild.Cpp`.

cpp/autobuilder/README.md

@@ -30,9 +30,9 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Autobuild.CSharp.Tes
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Extraction.CSharp.DependencyStubGenerator", "extractor\Semmle.Extraction.CSharp.DependencyStubGenerator\Semmle.Extraction.CSharp.DependencyStubGenerator.csproj", "{0EDA21A3-ADD8-4C10-B494-58B12B526B76}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Autobuild.Cpp", "..\cpp\autobuilder\Semmle.Autobuild.Cpp\Semmle.Autobuild.Cpp.csproj", "{125C4FB7-34DA-442A-9095-3EA1514270CD}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Autobuild.Cpp", "\autobuilder\Semmle.Autobuild.Cpp\Semmle.Autobuild.Cpp.csproj", "{125C4FB7-34DA-442A-9095-3EA1514270CD}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Autobuild.Cpp.Tests", "..\cpp\autobuilder\Semmle.Autobuild.Cpp.Tests\Semmle.Autobuild.Cpp.Tests.csproj", "{72F369B7-0707-401A-802F-D526F272F9EE}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Semmle.Autobuild.Cpp.Tests", "autobuilder\Semmle.Autobuild.Cpp.Tests\Semmle.Autobuild.Cpp.Tests.csproj", "{72F369B7-0707-401A-802F-D526F272F9EE}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

csharp/CSharp.sln

@@ -21,6 +21,6 @@
 
   <ItemGroup>
     <ProjectReference Include="..\Semmle.Autobuild.Cpp\Semmle.Autobuild.Cpp.csproj" />
-    <ProjectReference Include="..\..\..\csharp\autobuilder\Semmle.Autobuild.Shared\Semmle.Autobuild.Shared.csproj" />
+    <ProjectReference Include="..\..\autobuilder\Semmle.Autobuild.Shared\Semmle.Autobuild.Shared.csproj" />
   </ItemGroup>
 </Project>