Enfore minCompileSdk version when depending on ExoPlayer/Media3 libs

If an app sets a compileSdkVersion that is lower than the one used to
create AARs of its dependencies, the build process may produce invalid
outputs, for example by stripping methods from the APK that are only
called when the app is running on a new API version.

To avoid this issue, we can enforce that the compileSdk of apps or
libraries depending on ExoPlayer/Media3 is at least the same as the
one we used for compilation when creating the AAR.

Issue: google/ExoPlayer#10684
PiperOrigin-RevId: 485100067
(cherry picked from commit 136b8c5)

Author: tonihei

RELEASENOTES.md

@@ -26,6 +26,8 @@ Release notes
     *   Send missing `onMediaItemTransition` callback when calling `seekToNext`
         or `seekToPrevious` in a single-item playlist
         ([#10667](https://github.com/google/ExoPlayer/issues/10667)).
+    *   Enforce minimum `compileSdkVersion` to avoid compilation errors
+        ([#10684](https://github.com/google/ExoPlayer/issues/10684)).
 *   Downloads:
     *   Fix potential infinite loop in `ProgressiveDownloader` caused by
         simultaneous download and playback with the same `PriorityTaskManager`

common_library_config.gradle

@@ -22,6 +22,9 @@ android {
         targetSdkVersion project.ext.targetSdkVersion
         consumerProguardFiles 'proguard-rules.txt'
         testInstrumentationRunner 'androidx.test.runner.AndroidJUnitRunner'
+        aarMetadata {
+            minCompileSdk = project.ext.compileSdkVersion
+        }
     }
 
     compileOptions {