[Xamarin.Android.Build.Tasks] Add support for $(AndroidEnableObsolete…

…OverrideInheritance). (#8393)

Context: dotnet/java-interop@8e63cc8
Context: dotnet/java-interop@d0231c5

dotnet/java-interop@d0231c5c updated generator output so that
`[Obsolete]` would automagically "flow" to derived types and method
overrides, so that [warning CS0672][0] would not be emitted.

Before dotnet/java-interop@d0231c5c, we would emit:

	public class Context {
	  [Obsolete]
	  public virtual void SetWallpaper () { … }
	}

	public class ContextWrapper : Context {
	  [ObsoletedOSPlatform ("android23.0")]
	  public override void SetWallpaper () { … }
	}

`ContextWrapper.SetWallpaper()` would elicit a CS0672 warning:

	warning CS0672: Member 'ContextWrapper.SetWallpaper()' overrides obsolete member 'Context.SetWallpaper()'.
	Add the Obsolete attribute to 'ContextWrapper.SetWallpaper()'

With dotnet/java-interop@d0231c5c, we now emit the following, which
no longer emits CS0672:

	public class Context {
	  [Obsolete]
	  public virtual void SetWallpaper () { … }
	}

	public class ContextWrapper : Context {
	  [Obsolete]
	  public override void SetWallpaper () { … }
	}

While we feel that this is a nice improvement, this broke some
customers who didn't want their bindings to automatically gain
`[Obsolete]` "just because" they were overriding `[Obsolete]`
types or members.

In dotnet/java-interop@8e63cc8d, we added the ability to globally
*opt-out* of this new behavior by using
`generator --lang-features=do-not-fix-obsolete-overrides`.

Add a new `$(AndroidEnableObsoleteOverrideInheritance)` MSBuild
property.  When False, this adds
`generator --lang-features=do-not-fix-obsolete-overrides`,
preventing the automatic CS0672 fix behavior.

By default `$(AndroidEnableObsoleteOverrideInheritance)` is True.

[0]: https://learn.microsoft.com/en-us/dotnet/csharp/misc/cs0672

Documentation/guides/building-apps/build-properties.md

@@ -469,6 +469,15 @@ Support for this property was added in Xamarin.Android 5.1.
 
 This property is `False` by default.
 
+## AndroidEnableObsoleteOverrideInheritance
+
+A boolean property that determines if bound methods automatically inherit `[Obsolete]`
+attributes from methods they override.
+
+Support for this property was added in .NET 8.
+
+This property is `True` by default.
+
 ## AndroidEnablePreloadAssemblies
 
 A boolean property that controls

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Bindings.Core.targets

@@ -99,6 +99,7 @@ It is shared between "legacy" binding projects and .NET 5 projects.
         EnableBindingNestedInterfaceTypes="$(AndroidBoundInterfacesContainTypes)"
         EnableBindingInterfaceConstants="$(AndroidBoundInterfacesContainConstants)"
         EnableRestrictToAttributes="$(AndroidEnableRestrictToAttributes)"
+        EnableObsoleteOverrideInheritance="$(AndroidEnableObsoleteOverrideInheritance)"
         Nullable="$(Nullable)"
         UseJavaLegacyResolver="$(_AndroidUseJavaLegacyResolver)"
         NamespaceTransforms="@(AndroidNamespaceReplacement)"

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.DefaultProperties.targets

@@ -39,6 +39,7 @@
     <AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods Condition=" '$(AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods)' == '' ">true</AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods>
     <AndroidBoundInterfacesContainTypes Condition=" '$(AndroidBoundInterfacesContainTypes)' == '' ">true</AndroidBoundInterfacesContainTypes>
     <AndroidBoundInterfacesContainConstants Condition=" '$(AndroidBoundInterfacesContainConstants)' == '' ">true</AndroidBoundInterfacesContainConstants>
+    <AndroidEnableObsoleteOverrideInheritance Condition=" '$(AndroidEnableObsoleteOverrideInheritance)' == '' ">true</AndroidEnableObsoleteOverrideInheritance>
     <AndroidEnableRestrictToAttributes Condition=" '$(AndroidEnableRestrictToAttributes)' == '' ">obsolete</AndroidEnableRestrictToAttributes>
 
     <!-- Mono components -->

src/Xamarin.Android.Build.Tasks/Tasks/Generator.cs

@@ -52,6 +52,7 @@ public class BindingsGenerator : AndroidDotnetToolTask
 		public bool EnableBindingNestedInterfaceTypes { get; set; }
 		public bool EnableBindingInterfaceConstants { get; set; }
 		public string EnableRestrictToAttributes { get; set; }
+		public bool EnableObsoleteOverrideInheritance { get; set; }
 		public string Nullable { get; set; }
 
 		public ITaskItem[] TransformFiles { get; set; }
@@ -217,6 +218,9 @@ protected override string GenerateCommandLineCommands ()
 					if (EnableBindingStaticAndDefaultInterfaceMethods)
 						features.Add ("default-interface-methods");
 
+					if (!EnableObsoleteOverrideInheritance)
+						features.Add ("do-not-fix-obsolete-overrides");
+
 					if (string.Equals (EnableRestrictToAttributes, "obsolete", StringComparison.OrdinalIgnoreCase))
 						features.Add ("restrict-to-attributes");