L2CAP: Add Classic Link Manager Implementation

* Implement ClassicLinkManager and APIs for classic fixed channel
* Implement mechanism to create new ACL connections using ACL manager
* Updated dependencies among internal L2CAP components
* Remove SetOnChannelFail() and other unused methods from
  ClassicFixedChannelServiceImpl
* Add mocks and unit tests to verify the functionality of
  ClassicLinkManager
* Add common/testing/bind_test_util.h so that we can bind lambdas with
  capture in unit tests, although this is not allowed in production code
* Add error and result code for classic fixed channel service
  registration failure and connection failures

Bug: 138261142
Test: bluetooth_test_gd, cert/run_cert.sh
Change-Id: Ib2794a0073dbc73f46b8c6fd5f5cf0ae1c8c559a