Add Swappy & Pre-Transformed Swapchain

- Adds Swappy for Android for stable frame pacing
- Implements pre-transformed Swapchain so that Godot's compositor is in
charge of rotating the screen instead of Android's compositor
(performance optimization for phones that don't have HW rotator)

============================

The work was performed by collaboration of TheForge and Google. I am
merely splitting it up into smaller PRs and cleaning it up.

Changes from original PR:

- Removed "display/window/frame_pacing/android/target_frame_rate" option
to use Engine::get_max_fps instead.
- Target framerate can be changed at runtime using Engine::set_max_fps.
- Swappy is enabled by default.
- Added documentation.
- enable_auto_swap setting is replaced with swappy_mode.

.github/workflows/android_builds.yml

@@ -24,19 +24,19 @@ jobs:
             cache-name: android-editor
             target: editor
             tests: false
-            sconsflags: arch=arm64 production=yes
+            sconsflags: arch=arm64 production=yes swappy=yes
 
           - name: Template arm32 (target=template_release, arch=arm32)
             cache-name: android-template-arm32
             target: template_release
             tests: false
-            sconsflags: arch=arm32
+            sconsflags: arch=arm32 swappy=yes
 
           - name: Template arm64 (target=template_release, arch=arm64)
             cache-name: android-template-arm64
             target: template_release
             tests: false
-            sconsflags: arch=arm64
+            sconsflags: arch=arm64 swappy=yes
 
     steps:
       - name: Checkout
@@ -59,6 +59,17 @@ jobs:
       - name: Setup Python and SCons
         uses: ./.github/actions/godot-deps
 
+      - name: Download pre-built Android Swappy Frame Pacing Library
+        uses: dsaltares/fetch-gh-release-asset@1.1.2
+        with:
+          repo: darksylinc/godot-swappy
+          version: tags/v2023.3.0.0
+          file: godot-swappy.7z
+          target: swappy/godot-swappy.7z
+
+      - name: Extract pre-built Android Swappy Frame Pacing Library
+        run: 7za x -y swappy/godot-swappy.7z -o${{github.workspace}}/thirdparty/swappy-frame-pacing
+
       - name: Compilation
         uses: ./.github/actions/godot-build
         with: