upload to Google Play with GitHub Actions, remove Bitrise (#4682)

closes https://github.com/tuskyapp/Tusky/issues/4236

I hope I did everything correctly, we will find out after this is
merged.

I am setting up the environment variables containing the keys so they
are only available to actions that need them.

This should be easier to maintain, GitHub seems to be faster then
Bitrise, and we no longer have two checks on every pull request.

.github/workflows/deploy-test.yml

@@ -0,0 +1,45 @@
+# Deploy Tusky Nightly on each push to develop
+
+name: Deploy Tusky Nightly to Google Play
+
+on:
+  push:
+    branches:
+      - develop
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: ./.github/workflows/check-and-build.yml
+
+      - name: Build Green aab
+        run: ./gradlew app:bundleGreenRelease
+
+      - uses: r0adkll/sign-android-release@f30bdd30588842ac76044ecdbd4b6d0e3e813478
+        name: Sign Tusky Green aab
+        id: sign_aab
+        with:
+          releaseDirectory: app/build/outputs/bundle/greenRelease
+          signingKeyBase64: ${{ secrets.KEYSTORE }}
+          alias: ${{ secrets.KEY_ALIAS }}
+          keyStorePassword: ${{ secrets.KEYSTORE_PASSWORD }}
+          keyPassword: ${{ secrets.KEY_PASSWORD }}
+
+      - name: Generate whatsnew
+        id: generate-whatsnew
+        run: |
+          mkdir whatsnew
+          git log -3 --pretty=%B | head -c 500 > whatsnew/whatsnew-en-US
+
+      - name: Upload AAB to Google Play
+        id: upload-release-asset-aab
+        uses: r0adkll/upload-google-play@v1.1.3
+        with:
+          serviceAccountJsonPlainText: ${{ secrets.SERVICE_ACCOUNT_JSON }}
+          packageName: com.keylesspalace.tusky.test
+          releaseFiles: ${{steps.sign_aab.outputs.signedReleaseFile}}
+          track: production
+          whatsNewDirectory: whatsnew
+          status: completed
+          mappingFile: app/build/outputs/mapping/blueGoogleRelease/mapping.txt