[workload] Add Microsoft.Android.Runtimes framework

[pjcollins]

Context: dotnet/sdk#24077

A new "architecture-less" runtime pack has been added to distribute
Mono.Android.dll and other assemblies that are not architecture specific.

To support this, a new Microsoft.Android.Runtimes FrameworkReference
has been added to include our architecture specific runtime packs. The
existing Microsoft.Android FrameworkReference has been updated to
bring in the new runtime pack instead.

Shipping only one copy of Mono.Android.dll should cut down our workload
size by nearly 100MB compressed, and even more on disk.

With the size reductions the CoreCLR and NativeAOT runtime packs will
now be installed by the workload by default to avoid the need to
configure custom feeds to get these packs.

[pjcollins]

@jonathanpeppers I haven't yet sorted out why PackageNamingPolicy("LowercaseMD5") is now failing, but I think this is ready for some early feedback/review whenever you have some time, thanks!

[pjcollins]

Assuming the latest tests look good I think this should mostly be good to go

[pjcollins]

Rough workload pack compressed size change summary with changes to ship only one Mono.Android.dll:

• New managed runtime pack added: 9MB
• Four CoreCLR runtime packs: 38MB -> 4MB
• Four Mono runtime packs: 44MB -> 12MB
• Four NativeAOT runtime packs: 36MB -> 1.5MB

[jonathanpeppers]

With the size saving, could we just put the NativeAOT/CoreCLR packs in the workload:

android/src/Xamarin.Android.Build.Tasks/Microsoft.NET.Sdk.Android/WorkloadManifest.in.json

Lines 6 to 16 in d3483bc

	"packs": [
	"Microsoft.Android.Sdk.net10",
	"Microsoft.Android.Sdk.net9",
	"Microsoft.Android.Ref.36",
	"Microsoft.Android.Runtime.36.android",
	"Microsoft.Android.Runtime.Mono.36.android-arm",
	"Microsoft.Android.Runtime.Mono.36.android-arm64",
	"Microsoft.Android.Runtime.Mono.36.android-x86",
	"Microsoft.Android.Runtime.Mono.36.android-x64",
	"Microsoft.Android.Templates"
	],

These were restoring on the first build, but if they are so small now let's just install them to avoid messing with feeds for nightly builds?

Otherwise, this looks good to me, can it be taken out of draft? 😄

[pjcollins]

One other thing worth noting for our future selves, when .NET 11 comes around I think we'll need to update this section to also include this new Microsoft.Android.Runtimes fx:

android/src/Xamarin.Android.Build.Tasks/Microsoft.NET.Sdk.Android/WorkloadManifest.in.targets

Lines 13 to 19 in aa0485f

	<ItemGroup Condition=" '$(TargetPlatformIdentifier)' == 'android' and $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '9.0')) ">
	<KnownFrameworkReference
	Update="Microsoft.Android"
	LatestRuntimeFrameworkVersion="@NET_PREVIOUS_VERSION@"
	TargetingPackVersion="@NET_PREVIOUS_VERSION@"
	/>
	</ItemGroup>