hci: use bool for le_advertisements_active and le_advertisements_enabled

hci: store LE Set Address Resolution Enable supported

gap: make bd_addr_t const where possible

gap: defer whitelist update for connect with whitelist until create connection cancel has completed

gap: fix gap_scan_params if called before stack has started up, preserve scan type

gap: streamline adv/scan/connection management

gap: drop adv enable/disable todos, simplify adv management

gap: enable whitelist management for Central and Peripheral roles

gap: new gap_set_scan_params allows to specify scanning filter policy

hci: track le connection request in addition to le connection state

gap: request role change for classic connection via `gap_request_role`

gap: add gap_pin_code_response_binary, fixes issue #307 / pull request #238

hci: fix remote_supported_features in hci_stack_t

hci: request authentication after read encryption key size if not already authenticated

hci: track remote feature Secure Connections (Host) and (Controller)

hci: track remote extended features flag

hci: move eSCO remote feature into remote supported feature bit field

hci: split request remote supported features into read features page 0, 1, and 2

hci: clarify BONDING_REMOTE_SUPPORTS_SSP as BONDING_REMOTE_SUPPORTS_SSP_CONTROLLER

gap: add gap_secure_connections_enable

Revert "hci: write secure connections host enable if command supported"

This reverts commit 47bc3ebbd9c7203e97682307a2d63374390b5ae3.

hci: write secure connections host enable if command supported

hci: check if Read Remote Extended Features Command is implemented

GAP: gap_set_security_level sets required security level for incoming and outgoing connections

hci: implement ENABLE_LE_LIMIT_ACL_FRAGMENT_BY_MAX_OCTETS