hci: postpone hci remote features query until requested by l2cap

l2cap: move 'abort on conn request if not encrypted' check into l2cap_handle_remote_supported_features_received

hci: add hci_remote_features_available and use in l2cap

l2cap: send connection pending if remote features are not available for incoming connection

l2cap: add prototype for l2cap_handle_security_level_incoming_sufficient

l2cap: track conn request pending sent

l2cap: use #defines for L2CAP_CHANNEL_STATE_VAR_INCOMING

l2cap: packet send functions return status

l2cap: use bool for can send now functions

l2cap: use bool for l2cap_reserve_packet_buffer

l2cap: send pairing failed if security manager not registered

l2cap: support SMP over BR

l2cap: generalize fixed channel type for LE and BR/EDR

l2cap: mark some functions as Classic-only

l2cap: prefix globals, update deinit function

l2cap: directly accept incoming connections if security level is sufficient (without gap_request_security_level)

l2cap: extract l2cap_handle_security_level_incoming_sufficient

fix unused warnings

# Conflicts:
# src/l2cap.c

l2cap: update API docu and log messages

l2cap: track minimal security level

l2cap: don't trigger hci disconnect if l2cap security requirements are insufficient

l2cap: streamline secure connections only mode

If SC Only Mode is enabled, map all security levels to level 4 unless it is level 0

MISRAC2012-Rule-8.3_b: match function declaration and definition

l2cap: disconnect incoming connection in security mode 4 only if not connection is insecure and device is not bonded

l2cap: return unknown mandatory option in config response