GHA: Ad-hoc build (#5456)

Task/Issue URL:
https://app.asana.com/0/1174433894299346/1209097575356124/f

### Description
Adds a workflow that generates a release build from a ref passed as
input parameter

### Steps to test this PR
See builds in Asana task

.github/workflows/build-ad-hoc.yml

@@ -0,0 +1,66 @@
+name: Build - Ad-hoc release
+
+on:
+  workflow_dispatch:
+    inputs:
+      ref:
+        description: 'Ref to build APK from (branch, tag, commit)'
+        required: true
+        default: 'develop'
+
+env:
+  ASANA_PAT: ${{ secrets.GH_ASANA_SECRET }}
+  GOOGLE_APPLICATION_CREDENTIALS: '#{ENV["HOME"]}/jenkins_static/com.duckduckgo.mobile.android/ddg-upload-firebase.json'
+  GH_TOKEN: ${{ secrets.GT_DAXMOBILE }}
+
+jobs:
+  build-apk:
+    name: Generate and upload universal APK to GH Action Run
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+          token: ${{ secrets.GT_DAXMOBILE }}
+          ref: ${{ github.event.inputs.app-version }}
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'adopt'
+
+      - name: Create folder
+        if: always()
+        run: mkdir apk
+
+      - name: Decode keys
+        uses: davidSchuppa/base64Secret-toFile-action@v2
+        with:
+          secret: ${{ secrets.FAKE_RELEASE_PROPERTIES }}
+          fileName: ddg_android_build.properties
+          destination-path: $HOME/jenkins_static/com.duckduckgo.mobile.android/
+
+      - name: Decode key file
+        uses: davidSchuppa/base64Secret-toFile-action@v2
+        with:
+          secret: ${{ secrets.FAKE_RELEASE_KEY }}
+          fileName: android
+          destination-path: $HOME/jenkins_static/com.duckduckgo.mobile.android/
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v3
+
+      - name: Assemble release APK
+        run: ./gradlew assemblePlayRelease -Pforce-default-variant
+
+      - name: Move APK to new folder
+        run: find . -name "*.apk"  -exec mv '{}' apk/release.apk \;
+
+      - name: Upload debug apk
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: release
+          path: apk/release.apk