Implement onCountryCodeChanged() callback in tests

Setup the tests to invoke the onCountryCodeChanged() callback.

Currently the unit tests emulate the mUwbCountryCode.setCountryCode()
call by setting up the return value. This however misses that when the
country code is valid, this will call will result in an inline
invocation of the onCountryCodeChanged() callback.

Test: atest ServiceUwbTests
Bug: 275428627
Change-Id: Ie03383945802207998a7dabe5afc823781095e3c
1 file changed