L2CAP: Use AddressWithType in L2CAP LE APIs

* Bluetooth Low Energy connections always require explicit AddressType
  information
* Replacing existing Address and AddressType arguments in l2cap::le
  stack with hci::AddressWithType objects for easier hashing and
  managment

Bug: 140938432
Test: bluetooth_test_gd
Change-Id: I87ce02f0a0c867053a2b3560886924a566881801