⚡️ Enables gaplessPlayback by default for image assets (#569)

## What does this change?

Image assets are finalized during builds, they cannot be changed during
the runtime. The `gaplessPlayback` defaults to `false` which might lead
to images flashing between routes when the provider changes, which it
doesn't in fact.

Now we change it to `true` to ignore changes to provide a good display
experience. This can also considered as a non-breaking change in most
cases.

## Type of change

- [x] New feature (non-breaking change which adds functionality)

Author: AlexV525

examples/example/lib/gen/assets.gen.dart

@@ -247,7 +247,7 @@ class AssetGenImage {
     ImageRepeat repeat = ImageRepeat.noRepeat,
     Rect? centerSlice,
     bool matchTextDirection = false,
-    bool gaplessPlayback = false,
+    bool gaplessPlayback = true,
     bool isAntiAlias = false,
     String? package,
     FilterQuality filterQuality = FilterQuality.low,

examples/example_resources/lib/gen/assets.gen.dart

@@ -94,7 +94,7 @@ class AssetGenImage {
     ImageRepeat repeat = ImageRepeat.noRepeat,
     Rect? centerSlice,
     bool matchTextDirection = false,
-    bool gaplessPlayback = false,
+    bool gaplessPlayback = true,
     bool isAntiAlias = false,
     @Deprecated('Do not specify package for a generated library asset')
     String? package = package,

packages/command/example/lib/gen/assets.gen.dart

@@ -57,7 +57,7 @@ ${isPackage ? "\n  static const String package = '$packageName';" : ''}
     ImageRepeat repeat = ImageRepeat.noRepeat,
     Rect? centerSlice,
     bool matchTextDirection = false,
-    bool gaplessPlayback = false,
+    bool gaplessPlayback = true,
     bool isAntiAlias = false,
     ${isPackage ? deprecationMessagePackage : ''}
     String? package$packageParameter,