Add stack/acl/btm_acl APIs

acl_address_from_handle(uint16_t hci_handle);
acl_power_mode_from_handle(uint16_t hci_handle);

Working towards encapsulation of tACL_CONN

Bug: 159815595
Tag: #refactor
Test: compile & verify basic functions working
Change-Id: Id0847f16ee181a72bdc7032cf13706cdbc29e6ec