Treblize media codec list file location

Treblization requires to locate partner-specific configs in its own
partition. So the media codec list file could be located in /odm/etc
or /vendor/etc.
This CL is to support those locations for the config.

Test: building succeeded and tested on sailfish.
CTS test (MediaCodecListTest) was passed as well.
Bug: 35369237

Change-Id: Ifd307e2aae2ab65039a02b9a55fcc16895f83dbf