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

d70db5b was *wrong* in that it merged two different things:

* Java stub generation's "codegen target" (now settable by an MSBuild
  property `$(_AndroidCodeGenerationTarget)`)

* 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 `$(_AndroidJcwCodegenTarget)=JavaInterop1`
and `$(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

@@ -1516,7 +1516,7 @@ because xbuild doesn't support framework reference assemblies.
 
   <GenerateJavaStubs
       AndroidRuntime="$(_AndroidRuntime)"
-      CodeGenerationTarget="$(AndroidCodegenTarget)"
+      CodeGenerationTarget="$(_AndroidJcwCodegenTarget)"
       ResolvedAssemblies="@(_ResolvedAssemblies)"
       ResolvedUserAssemblies="@(_ResolvedUserMonoAndroidAssemblies)"
       ErrorOnCustomJavaObject="$(AndroidErrorOnCustomJavaObject)"