att_server: fix signed vs. unsigned warnings

att_server: move att_server_eatt_bearer_t to header, document att_server_eatt_init

att_server: fix assert

att_server: add missing include

att_server: improve handling of pending response

att_server: extract att_server_handle_response_pending

att_server: allow to start crypto operation from delayed att read/write request

# Conflicts:
# CHANGELOG.md

att_sever: call att_read_callback on services with ATT_READ_RESPONSE_PENDING

# Conflicts:
# CHANGELOG.md

att_server: add flags to att_service_handler_t

Use boolean for conditionals

att_server: use bool for ir_lookup_active and pairing_active

att_server: forward HCI_SUBEVENT_LE_CONNECTION_COMPLETE for backwards compatibility

cmake: fix warnings, code cleanup

core: use GAP_SUBEVENT_LE_CONNECTION_COMPLETE instead of HCI_SUBEVENT_LE_CONNECTION_COMPLETE

att_server: reject incoming eatt connection if outgoing connection is active

att_dispatch: update att_server.l2cap_cid in lower layer

att_server: move classic packet handling into att dispatch handler

att_server: use can send / request to send from att dispatch

att_server: register classic att server via att_dispatch

l2cap: add authorization_required param to ecbm service registration

att_server: clear persistent ccc on new pairing (fix regression from cd45e970)

att_server: set att_connection for att_run_for_context

att_server: use eatt bearer for notify/indicate if available

att_server: extract att_server_prepare_server_message that uses eatt bearer if available

att_server: add att_server_multiple_notify