component/bt: add AVRC event for remote features indication

component/bt: add AVRC event for remote features indication

1. remove the feature mask parameter from AVRC connection state event, as the AVCTP connection can be initiated by remote device before service discovery to remote device is performed. \
In this case, AVRCP connection state event may not be reported after connection initated by remote device is established.
2. remove ESP_AVRC_CT_MAX_EVT
3. add more documentations to AVRC APIs