Dev: use build product flavors for app store release (#1205)

## Description
Instead of applying a code patch, this PR uses build time [product
flavors](https://developer.android.com/build/build-variants#product-flavors)
to define the existing default and an app store variant. This is more
robust than maintaining a patch file and making sure it is applied
before building.

The app store variant applies the same code changes (removing install
permission, requiring leanback, & setting `UpdateChecker.ACTIVE`), but
via manifest placeholders/merging and `BuildConfig` entries.

There are no user facing changes.

### Related issues
None

### Testing
Built the variants and verified manifest changes via aapt

## Screenshots
N/A

## AI or LLM usage
None

.github/workflows/main.yml

@@ -54,7 +54,7 @@ jobs:
           ORG_GRADLE_PROJECT_WholphinExtensionsUsername: "${{ secrets.EXTENSIONS_USERNAME }}"
           ORG_GRADLE_PROJECT_WholphinExtensionsPassword: "${{ secrets.EXTENSIONS_PASSWORD }}"
         run: |
-          ./gradlew clean assembleRelease assembleDebug --no-daemon
+          ./gradlew clean assembleDefaultRelease assembleDefaultDebug --no-daemon
 
       - name: Verify signatures
         run: |
@@ -67,7 +67,7 @@ jobs:
           find app/build/outputs/apk -name '*.apk' -print0 |
             while IFS= read -r -d '' line; do
               # Wholphin-release-0.2.9-62-g5c12e03-16-arm64-v8a.apk => Wholphin-arm64-v8a.apk
-              short_name="$(echo $line | sed -E 's/-[0-9]+\.[0-9]+\.[0-9]+-[0-9]+-g[a-fA-F0-9]+-[0-9]+//')"
+              short_name="$(echo $line | sed -E 's/-[0-9]+\.[0-9]+\.[0-9]+-[0-9]+-g[a-fA-F0-9]+-[0-9]+//' | sed -E 's/-default//')"
               echo "$line => $short_name"
               cp "$line" "$short_name"
             done