Floss: replace HFP LC3 codec libraries with CodecClient.

In this patch, HFP LC3 codec libraries are replaced by |CodecClient|
methods. |CodecClient| inherits |MmcInterface|, and serves as a proxy of
codec server. MMC could be built with "USE=${USE} floss floss_mmc".

Bug: 294165109
Tag: #floss
Test: m - emerge and deploy floss on brya, connect to Pixel Buds,
check /var/log/messages to make sure btadapterd works when switch to HFP
LC3 codec.

Change-Id: I20bae03bf5252909559eb091ea314c2de8472ab4