These changes are also compatible with FFmpeg 5.1, which is now minimum supported version.
Also set -Wl,-Bsymbolic flag via target_link_options command which is more correct.
As most classes are used via interface only and people depending on it locally can always find the Javadoc in Android Studio directly, we don't plan to add Javadocs for these extensions module in developer.android.com.
PiperOrigin-RevId: 521993756
Also fixed the javadoc link in devsite and removed javadoc links from decoder extensions as it is not published yet on developer.android.com.
#minor-release
PiperOrigin-RevId: 520636868
