Add optional AV1 software decoding via dav1d for ExoPlayer (#721)

## Description
Adds the [`dav1d` decoder
module](https://github.com/androidx/media/tree/release/libraries/decoder_av1)
for ExoPlayer as an option. It can be enabled in advanced settings.

Performance will vary between devices.

### Related issues
Closes #103

### Dev notes

As with the ffmpeg module, this one is not required to build the entire
app so it's easier for developers to get started.

This also introduces a customized `DefaultRenderersFactory` for
ExoPlayer, but its largely copied from the super class's implementation.

.github/actions/native-build/action.yml

@@ -15,6 +15,25 @@ runs:
         path: |
           app/libs
         key: ${{ runner.os }}-ffmpeg-${{ hashFiles('**/libs.versions.toml', '**/scripts/ffmpeg/build_ffmpeg_decoder.sh') }}
+    - name: Load libmpv module cache
+      id: cache_libmpv_module
+      if: ${{ inputs.cache }}
+      uses: actions/cache/restore@v4
+      with:
+        path: |
+          app/src/main/libs
+        key: ${{ runner.os }}-libmpv-${{ hashFiles('**/scripts/mpv/*.sh', '**/scripts/mpv/include/*', '**/scripts/mpv/scripts/*', 'app/src/main/jni/*') }}
+    - name: Install dependencies
+      if: steps.cache_ffmpeg_module.outputs.cache-hit != 'true' || steps.cache_libmpv_module.outputs.cache-hit != 'true'
+      shell: bash
+      run: |
+        python -m pip install --upgrade pip
+        pip install jsonschema jinja2
+        sudo apt update
+        sudo apt install -y build-essential autoconf pkg-config libtool ninja-build unzip wget meson nasm
+
+
+# ffmpeg
     - name: Build ffmpeg decoder
       id: ffmpeg-decoder
       if: steps.cache_ffmpeg_module.outputs.cache-hit != 'true'
@@ -30,23 +49,7 @@ runs:
           app/libs
         key: ${{ steps.cache_ffmpeg_module.outputs.cache-primary-key }}
 
-    - name: Load libmpv module cache
-      id: cache_libmpv_module
-      if: ${{ inputs.cache }}
-      uses: actions/cache/restore@v4
-      with:
-        path: |
-          app/src/main/libs
-        key: ${{ runner.os }}-libmpv-${{ hashFiles('**/scripts/mpv/*.sh', '**/scripts/mpv/include/*', '**/scripts/mpv/scripts/*', 'app/src/main/jni/*') }}
-
-    - name: Install dependencies
-      if: steps.cache_libmpv_module.outputs.cache-hit != 'true'
-      shell: bash
-      run: |
-        python -m pip install --upgrade pip
-        pip install jsonschema jinja2
-        sudo apt update
-        sudo apt install -y build-essential autoconf pkg-config libtool ninja-build unzip wget meson
+# libmpv
     - name: Get libmpv dependencies
       if: steps.cache_libmpv_module.outputs.cache-hit != 'true'
       shell: bash