MPEG4Extractor: Add IAMF support from Android Baklava

Add IAMF parsing support to the MPEG4Extractor.
The feature is guarded by a runtime flag and enabled from Android Baklava.

FLAG:com.android.media.extractor.flags.extractor_mp4_enable_iamf
Bug: 428836838

Test: atest MediaExtractorTest

Change-Id: I5bc09d0958b664c7253a6c006a31a20559c4808f