workflows: Run android emulator tests on CI

Add a workflow that runs android emulator tests on CI. It is set
up to run only on changes to the android_jni/ subdirectory since
it's a bit slow (at least 15 minutes).

Add a note to android_jni/README.md about the maven hosted
version of the library (this forces the workflow to run on this
change).
diff --git a/.github/workflows/ci-android-emulator-tests.yml b/.github/workflows/ci-android-emulator-tests.yml
new file mode 100644
index 0000000..2aba168
--- /dev/null
+++ b/.github/workflows/ci-android-emulator-tests.yml
@@ -0,0 +1,52 @@
+name: CI
+on:
+  push:
+    paths:
+      - 'android_jni/**'
+  pull_request:
+    paths:
+      - 'android_jni/**'
+
+permissions:
+  contents: read
+
+jobs:
+  build-and-run-android-jni-tests:
+    runs-on: macos-latest
+    strategy:
+      fail-fast: false
+
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@v3
+      - name: Download and Setup the Android NDK
+        uses: nttld/setup-ndk@v1
+        id: setup-ndk
+        with:
+          ndk-version: r23b
+          add-to-path: false
+      - name: Setup ninja
+        uses: seanmiddleditch/gha-setup-ninja@v3
+      - name: Setup cmake
+        uses: jwlawson/actions-setup-cmake@v1.13
+        with:
+          # This is the minimum cmake version needed to build libgav1.
+          cmake-version: '3.7.x'
+      - name: Build libgav1 with the Android NDK
+        working-directory: ext
+        run: bash libgav1_android.sh ${{ steps.setup-ndk.outputs.ndk-path }}
+      - name: Setup JDK
+        uses: actions/setup-java@v3
+        with:
+          java-version: '11'
+          distribution: 'zulu'
+      - name: Run Instrumented Tests on the Emulator
+        uses: reactivecircus/android-emulator-runner@v2.28.0
+        with:
+          working-directory: android_jni
+          api-level: 30
+          force-avd-creation: false
+          cmake: 3.18.1
+          ndk: 23.2.8568313
+          arch: x86_64
+          script: ./gradlew cAT
diff --git a/android_jni/README.md b/android_jni/README.md
index 9b8cfd9..963ec74 100644
--- a/android_jni/README.md
+++ b/android_jni/README.md
@@ -76,3 +76,8 @@
 The entire android_jni directory can be imported as a project into Android Studio.
 
 To build the project from within Android Studio, follow the all the steps from the above section to checkout and build libgav1. After that, the last step is equivalent to invoking the build from Android Studio.
+
+## Maven Releases
+
+Maven hosted version of libavif can be found here:
+https://repo1.maven.org/maven2/org/aomedia/avif/android/avif/