APM test: Fix default config, add test for 'dump'

 - Fix AudioPolicyConfig::setDefault so the config is valid again;

 - Enhance the default config with dynamic profiles;

 - Factor out the code for creating a full dynamic profile;

 - Add a method to unit test that verifies calling APM::dump.
   This is also useful to examine how the default config looks
   like.

Test: audiopolicy_tests
Change-Id: I102071e160b835da50ed5806bd2d62102a10d775