Enable FLAC and AAC decoding (flag-gated) in the Codec2 IAMF decoder.

Also use libFraunhoferAAC and libFLAC as shared libraries in their
codec2 decoders.

Bug: 396187214
Flag: android.media.swcodec.flags.iamf_aac_flac
Test: build
Change-Id: I8572096c68bbe1dfd2ee8deafe204606a63337bd