Look for additional media codec XML files

media_codecs_overlay.xml in /product and /odm directories
media_codecs_overlay.xml under /apex/com.android.media/etc/formatshaper
(all optional)

Bug: 182827840
Test: atest XMLParserTest
Test: atest ccodec_unit_test
Test: atest mc_sanity_test
Change-Id: I689b3dd7ae5902043e376c3c7b473894f58c6e52