[build] Replace Android tools GitInfo versioning

[jonathanpeppers]

Summary

• replace GitInfo-based Android tooling versions with <Android major>.<Android minor>.<commit distance>
• use the same version for plain DLL builds and the AndroidSdk NuGet package
• remove the GitInfo fallback files and avoid the XAVersionInfo bootstrap dependency
• fall back to distance 0 in shallow checkouts where Git history cannot provide the real distance

Full-history builds currently produce 37.0.2346.0; shallow CI builds produce 37.0.0.0 instead of failing.

Validation

• dotnet build src\Microsoft.Android.Build.BaseTasks\Microsoft.Android.Build.BaseTasks.csproj -c Debug
• dotnet build src\Xamarin.Android.Tools.AndroidSdk\Xamarin.Android.Tools.AndroidSdk.csproj -c Debug
• dotnet pack src\Xamarin.Android.Tools.AndroidSdk\Xamarin.Android.Tools.AndroidSdk.csproj -c Debug --no-build
• built both projects from a depth-1 clone to reproduce the Azure Pipelines checkout

[Copilot]

Pull request overview

This PR changes how Android tooling assemblies and the Xamarin.Android.Tools.AndroidSdk NuGet package derive their versions, moving away from XAVersionInfo/GitInfo-based versioning toward a version format based on Android major/minor plus commit distance.

Changes:

• Removed XAVersionInfo.targets imports from the Android tooling projects and centralized version computation in Xamarin.Android.Tools.Versioning.targets.
• Replaced GitInfo-based versioning with MSBuild Exec calls that compute PackVersionCommitCount from eng/Versions.props.
• Deleted per-project GitInfo.txt fallback files for the affected tooling projects.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Xamarin.Android.Tools.AndroidSdk/Xamarin.Android.Tools.AndroidSdk.csproj	Drops XAVersionInfo.targets import; relies on shared tooling versioning targets.
src/Xamarin.Android.Tools.AndroidSdk/GitInfo.txt	Removes GitInfo fallback file for this project.
src/Microsoft.Android.Build.BaseTasks/Microsoft.Android.Build.BaseTasks.csproj	Drops XAVersionInfo.targets import; relies on shared tooling versioning targets.
src/Microsoft.Android.Build.BaseTasks/GitInfo.txt	Removes GitInfo fallback file for this project.
build-tools/scripts/Xamarin.Android.Tools.Versioning.targets	Implements new git-based commit-distance version calculation and sets Version/PackageVersion.

Suppressed comments (1)

build-tools/scripts/Xamarin.Android.Tools.Versioning.targets:31

• ❌ error — git blame can return a boundary revision prefixed with ^ (the previous GitCommitsInRange task explicitly mentions this case), which will make git rev-list --count $(_AndroidPackVersionCommit)..HEAD fail and break builds. Sanitize the commit hash and handle exit code 128 by falling back to 0 (matching prior behavior), while still failing for other git errors.

      <_AndroidPackVersionCommit>%(_AndroidPackVersionBlameLine.CommitHash)</_AndroidPackVersionCommit>
    </PropertyGroup>
    <Exec
        Command="git rev-list --count $(_AndroidPackVersionCommit)..HEAD"
        ConsoleToMSBuild="true"