Feature: send delay report once configed

As accept device, sending delay report after setconfig rsp
is sent. Do it as a second action instead of in the
bta AV subsystem.

As init device,  send delay report after setconfig rsp
is received and just before sending open req.

Add UT to test the state machine;
- As accept, it shall send delay report after it sends setconfig rsp
- As init, it shall send delay report after it receives setconfig rsp
  and before it sends open req

Also, correct delay report confirm event shall be called back

To run the test, run atest [--host] net_test_stack_avdtp

Bug: 185507179
Bug: 188367563
Tag: #feature
Test: atest --host bluetooth_test_gd

Change-Id: Id0cb5bfc62b3a9296564b0e9651b30027d677f85