[Xamarin.Android.Build.Tasks] introduce $(_AndroidJcwCodegenTarget) (#9858)

Context: #9846
Context: dbb0b92
Context: d70db5b

While trying to *build* `tests/Mono.Android-Tests` with NativeAOT:

	dotnet-local.cmd build tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj ^
	  -p:TestsFlavor=NativeAOT -p:PublishAot=true -c Release -bl -t:Install

it would fail to build:

	tests\Mono.Android-Tests\Java.Interop-Tests\obj\Release\net10.0-android\generated\src\Net.Dot.Jni.Test.MyJavaInterfaceImpl.cs(19,81):
	error CS1056: Unexpected character '`'

The offending code?

	public partial class MyJavaInterfaceImpl : global::Java.Interop.JavaObjectArray`1, global::Net.Dot.Jni.Test.IJavaInterface {
	}

which is deeply, *deeply*, wrong.

Further investigation showed that the problem was that
`Java.Interop-Tests` was trying to bind Java code, and in this case
was using `generator --codegen-target=JavaInterop1` output.

This is output we've never tried to use before in .NET for Android;
`generator --codegen-target=JavaInterop1` is experimental
(and @jonpryor's playground; see dotnet/java-interop#858), and
shouldn't be used *now* (if ever).

Ultimately, we realized that commit d70db5b was *wrong*, in that it
merged two different things:

 1. Java stub generation's "codegen target", previously settable by
    an MSBuild property `$(_AndroidCodeGenerationTarget)`
    (introduced in dbb0b92)

 2. C# `generator`s "codegen target" or `$(AndroidCodegenTarget)`

The problem was `$(_AndroidCodeGenerationTarget)` was just poorly
named making me think it was the same as `$(AndroidCodegenTarget)`.

Partially revert d70db5b and use the name `$(_AndroidJcwCodegenTarget)`
instead.

NativeAOT now defaults to:

  * `$(_AndroidJcwCodegenTarget)=JavaInterop1`
  * `$(AndroidCodegenTarget)=XAJavaInterop1`

Author: jonathanpeppers

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

@@ -41,7 +41,8 @@
     <!-- Bindings properties -->
     <!-- jar2xml is not supported -->
     <AndroidClassParser>class-parse</AndroidClassParser>
-    <AndroidCodegenTarget Condition=" '$(AndroidCodegenTarget)' == '' and '$(_AndroidRuntime)' != 'NativeAOT' ">XAJavaInterop1</AndroidCodegenTarget>
+    <AndroidCodegenTarget Condition=" '$(AndroidCodegenTarget)' == '' ">XAJavaInterop1</AndroidCodegenTarget>
+    <_AndroidJcwCodegenTarget Condition=" '$(_AndroidJcwCodegenTarget)' == '' and '$(_AndroidRuntime)' != 'NativeAOT' ">XAJavaInterop1</_AndroidJcwCodegenTarget>
     <AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods Condition=" '$(AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods)' == '' ">true</AndroidBoundInterfacesContainStaticAndDefaultInterfaceMethods>
     <AndroidBoundInterfacesContainTypes Condition=" '$(AndroidBoundInterfacesContainTypes)' == '' ">true</AndroidBoundInterfacesContainTypes>
     <AndroidBoundInterfacesContainConstants Condition=" '$(AndroidBoundInterfacesContainConstants)' == '' ">true</AndroidBoundInterfacesContainConstants>

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

@@ -12,7 +12,7 @@ This file contains the NativeAOT-specific MSBuild logic for .NET for Android.
   <!-- Default property values for NativeAOT -->
   <PropertyGroup>
     <_AndroidRuntimePackRuntime>NativeAOT</_AndroidRuntimePackRuntime>
-    <AndroidCodegenTarget Condition=" '$(AndroidCodegenTarget)' == '' ">JavaInterop1</AndroidCodegenTarget>
+    <_AndroidJcwCodegenTarget Condition=" '$(_AndroidJcwCodegenTarget)' == '' ">JavaInterop1</_AndroidJcwCodegenTarget>
     <!-- .NET SDK gives: error NETSDK1191: A runtime identifier for the property 'PublishAot' couldn't be inferred. Specify a rid explicitly. -->
     <AllowPublishAotWithoutRuntimeIdentifier Condition=" '$(AllowPublishAotWithoutRuntimeIdentifier)' == '' ">true</AllowPublishAotWithoutRuntimeIdentifier>
     <!-- NativeAOT's targets currently gives an error about cross-compilation -->

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -1389,7 +1389,7 @@ because xbuild doesn't support framework reference assemblies.
     <_AndroidJarAndDexDirectory>$(_XATargetFrameworkDirectories)</_AndroidJarAndDexDirectory>
   </PropertyGroup>
   <GetMonoPlatformJar
-      Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(AndroidCodegenTarget)' == 'XAJavaInterop1' "
+      Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(_AndroidJcwCodegenTarget)' == 'XAJavaInterop1' "
       TargetFrameworkDirectory="$(_AndroidJarAndDexDirectory)">
     <Output TaskParameter="MonoPlatformJarPath" PropertyName="MonoPlatformJarPath" />
     <Output TaskParameter="MonoPlatformDexPath" PropertyName="MonoPlatformDexPath" />
@@ -1418,12 +1418,12 @@ because xbuild doesn't support framework reference assemblies.
   />
 
   <Copy
-    Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(AndroidCodegenTarget)' == 'XAJavaInterop1' "
+    Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(_AndroidJcwCodegenTarget)' == 'XAJavaInterop1' "
     SourceFiles="$(MonoPlatformJarPath)"
     DestinationFiles="$(IntermediateOutputPath)android\bin\mono.android.jar"
     SkipUnchangedFiles="true" />
   <Touch
-    Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(AndroidCodegenTarget)' == 'XAJavaInterop1' "
+    Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(_AndroidJcwCodegenTarget)' == 'XAJavaInterop1' "
     Files="$(IntermediateOutputPath)android\bin\mono.android.jar" />
 
   <Touch Files="$(_AndroidStaticResourcesFlag)" AlwaysCreate="true" />
@@ -1433,7 +1433,7 @@ because xbuild doesn't support framework reference assemblies.
     <FileWrites Include="$(_AndroidIntermediateJavaSourceDirectory)mono\JavaInteropTypeManager.java" />
     <FileWrites Include="$(MonoAndroidIntermediateAssemblyDir)machine.config" />
     <FileWrites
-        Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(AndroidCodegenTarget)' == 'XAJavaInterop1' "
+        Condition=" '$(_AndroidUseMarshalMethods)' != 'True' and '$(_AndroidJcwCodegenTarget)' == 'XAJavaInterop1' "
         Include="$(IntermediateOutputPath)android\bin\mono.android.jar"
     />
     <FileWrites Include="$(_AndroidStaticResourcesFlag)" />
@@ -1530,7 +1530,7 @@ because xbuild doesn't support framework reference assemblies.
 
   <GenerateJavaStubs
       AndroidRuntime="$(_AndroidRuntime)"
-      CodeGenerationTarget="$(AndroidCodegenTarget)"
+      CodeGenerationTarget="$(_AndroidJcwCodegenTarget)"
       ResolvedAssemblies="@(_ResolvedAssemblies)"
       ResolvedUserAssemblies="@(_ResolvedUserMonoAndroidAssemblies)"
       ErrorOnCustomJavaObject="$(AndroidErrorOnCustomJavaObject)"
@@ -1566,7 +1566,7 @@ because xbuild doesn't support framework reference assemblies.
       ApplicationLabel="$(_ApplicationLabel)"
       BundledWearApplicationName="$(BundledWearApplicationPackageName)"
       CheckedBuild="$(_AndroidCheckedBuild)"
-      CodeGenerationTarget="$(AndroidCodegenTarget)"
+      CodeGenerationTarget="$(_AndroidJcwCodegenTarget)"
       Debug="$(AndroidIncludeDebugSymbols)"
       EmbedAssemblies="$(EmbedAssembliesIntoApk)"
       EnableMarshalMethods="$(_AndroidUseMarshalMethods)"