Use branch-specific package ids for Auto test builds

[apollotsantos]

Adds branch-scoped Android Auto test build identifiers so CI APKs can be installed and tested independently from the official release.

Why this is useful:

• Android Auto/DHU test builds can conflict with the released app when they share the same package id but are signed differently. Giving CI test builds a separate package id makes them easier to install, discover, and validate in DHU.
• Building locally is inconvenient on ARM-based development machines because the Android/NDK toolchain is easiest to run reliably in the GitHub Actions environment. This keeps pipeline-built APKs practical for day-to-day testing.
• The package id is based on the fork owner and branch name, not the commit. That means new commits on the same branch update the same installed test app instead of creating a new app each time.
• The short commit is still shown in the generated app name and artifact name, so it remains easy to identify exactly which CI build is installed.

What changed:

• Computes a sanitized APP_ID_SFX in the APK workflow using the PR/fork owner and branch name.
• Passes APP_ID_SFX into both Auto release APK builds.
• Adds optional APP_NAME_SFX support so CI builds display owner/branch and short commit information in the app label.
• Includes the test identifier in uploaded artifact names.

Validation:

• Checked the edited workflow and Gradle file for reported editor errors.
• Ran git diff --check.
• Manually verified the package suffix sanitizer with branch names containing uppercase letters, slashes, hyphens, dots, and a leading number.

The actual APK build remains validated by the GitHub Actions pipeline.

[AndreyPavlenko]

Thanks