transcoding: move MediaTranscodeManager to apex

bug: 159172726
test: builds; presubmit; manual testing transcoding locally.
Change-Id: I727912a04cf4f7f03fdf5fa0a74e522f69dca66f
diff --git a/native/android/Android.bp b/native/android/Android.bp
index 6db4da9..3daaf05 100644
--- a/native/android/Android.bp
+++ b/native/android/Android.bp
@@ -103,7 +103,7 @@
     version_script: "libandroid.map.txt",
     stubs: {
         symbol_file: "libandroid.map.txt",
-        versions: ["29"],
+        versions: ["29", "31"],
     },
 }