[Mono.Android] Bind Android API-Baklava Beta 1 (#9707)

Context: https://developer.android.com/about/versions/16
Context: https://android-developers.googleblog.com/2025/01/first-beta-android16.html

Android 16 Beta 1 has been released.

  * [API-Baklava Beta 1 vs. API-35][0]
  * [API-Baklava Beta 1 vs. Developer Preview 2][1]

The Android 16 Preview Program Overview [Timeline and updates][2]
section suggests the following timeline:

  * Nov/Dec: Developer Previews
  * Jan/Feb: Unstable Betas
  * Mar/Apr: Stable Betas
  * ???: Final

Currently, this will be usable in its preview form to `main` users
who explicitly target `net10.0-android36`.  Once we are shipping
.NET 10 previews, it will be usable for users who explicitly target
`net10.0-android36`.

We still need to decide on our strategy for backporting this to
.NET 9 service releases.

Additional note(s):

  - We cannot generate an updated `PublicAPI.Unshipped.txt` because
    this is done within VS and current VS versions cannot load
    `net10.0` projects.
    
    We have temporarily disabled PublicAPI verification for unstable
    API levels until this is resolved.

[0]: https://developer.android.com/sdk/api_diff/b-beta1/changes
[1]: https://developer.android.com/sdk/api_diff/b-beta1-incr/changes
[2]: https://developer.android.com/about/versions/16/overview

Author: jpobst

build-tools/xaprepare/xaprepare/ConfigAndData/Dependencies/AndroidToolchain.cs

@@ -73,7 +73,7 @@ public AndroidToolchain ()
 				new AndroidPlatformComponent ("platform-33-ext3_r03",   apiLevel: "33", pkgRevision: "3"),
 				new AndroidPlatformComponent ("platform-34-ext7_r02",   apiLevel: "34", pkgRevision: "2"),
 				new AndroidPlatformComponent ("platform-35_r01",   apiLevel: "35", pkgRevision: "1", isLatestStable: true),
-				new AndroidPlatformComponent ("platform-Baklava_r03",   apiLevel: "Baklava", pkgRevision: "3", isLatestStable: true),
+				new AndroidPlatformComponent ("platform-Baklava_r04",   apiLevel: "Baklava", pkgRevision: "4", isLatestStable: true),
 
 				new AndroidToolchainComponent ("source-35_r01",
 					destDir: Path.Combine ("sources", "android-35"),

src/Mono.Android/Mono.Android.csproj

@@ -26,14 +26,16 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <DefineConstants Condition=" '$(AndroidApiLevel)' &gt; '$(AndroidLatestStableApiLevel)' ">$(DefineConstants);ANDROID_UNSTABLE</DefineConstants>
+    <IsUnstableVersion Condition=" '$(AndroidApiLevel)' &gt; '$(AndroidLatestStableApiLevel)' ">true</IsUnstableVersion>
+    <DefineConstants Condition=" '$(IsUnstableVersion)' == 'True' ">$(DefineConstants);ANDROID_UNSTABLE</DefineConstants>
     <OutputPath>$(_MonoAndroidNETDefaultOutDir)</OutputPath>
 
     <!-- Allow PublicApiAnalyzers to be turned off -->
     <RunAnalyzers Condition=" '$(DisableApiCompatibilityCheck)' == 'True' ">false</RunAnalyzers>
 
     <!-- PublicApiAnalyzers warnings should be errors, but building in VS throws incorrect extra warnings -->
-    <WarningsAsErrors Condition=" '$(BuildingInsideVisualStudio)' != 'True' ">$(WarningsAsErrors);RS0016,RS0017</WarningsAsErrors>
+    <!-- Temporarily ignore unstable version warnings until VS can build .NET 10 projects -->
+    <WarningsAsErrors Condition=" '$(BuildingInsideVisualStudio)' != 'True' AND '$(IsUnstableVersion)' != 'True' ">$(WarningsAsErrors);RS0016,RS0017</WarningsAsErrors>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(IncludeAndroidJavadoc)' == 'True' ">