Codec management when multiple devices are connected

Problem: For A2DP sink, when multiple devices are connected, there
is an issue of managing the codecs. The cached codec is updated based
on decoder update event. As a result, the active device's codec is
overriden with the other device codec. Also, when the active device
is changed, the decoder interface gets initailzed to null and doesn't
get re-initialized. As a result if muisc is played, then the stack
crashes.

Solution: Store the codec at peer device level and remove the single
cached codec. The codec is retrieved based on the peer address's
codec. Also, when a new session is started, then the decoder
interface is initialized. Subsequently, the packets are decoded
based on the device's codec information rather than the cached codec.

Test: m (launch seahawk-trunk-userdebug)

Bug: 302730596
Bug: 346409266
Bug: 339264791
Change-Id: Ibdf1db82547cbbbf5f38612b24587185d2dc87db