a2dp_source: fix reconfigure

avdtp: skip stream endpoints that are currently in use, mark when selected

a2dp_source: use local stream endpoint reference in connection struct

a2dp_source: store local stream endpoint in avdtp_connection

a2dp_source: ignore set config for invalid local cid

a2dp_source: reset discovery timer only for active connection

a2dp_source: reset sep_discovery_cid if no suitable sep found

a2dp_source: ENABLE_A2DP_SOURCE_EXPLICIT_CONFIG disables auto-config

a2dp_source: extract a2dp_source_set_config

a2dp_source: drop avdtp_stream_endpoint_context_t

a2dp_source: collect state for sep discovery

a2dp_source: use sep_discovery_cid instead of a2dp_source_cid

a2dp_source: move outgoing_active into avdtp_connection_t

a2dp_source: move stream_endpoint_configured into avdtp_connection_t

a2dp_source: move have_config into avdtp_connection_t

a2dp_source: use getter for outgoing_active, have_configuration, stream_configured

a2dp_source: drop simple a2dp_source_cid checks

a2dp_source: remove global a2dp_source_state

a2dp_source: use a2dp_source_state from connection

a2dp_source: lookup connection before access to a2dp_source_state

a2dp_source: mirror global a2dp_source_state in connection struct

a2dp_source: skip stream endpoints that are reported as 'in use' during configuration

a2dp_source: fix a2dp_source_establish_stream

a2dp_source_establish_stream did return an error if an avdtp connection exists, even if the previous attempt to setup a sep failed

a2dp/avdtp: mark capabilities as const

a2dp, avdtp: use `a2dp_source_set_config_{TYPE}` and `avdtp_config{TYPE}_store` to avoid large number of parameters