Refreshed UX for Audio Formats Setting [Backend]

This CL modifies getSurroundSound(reported=true) to always return formats
supported by device irrespective of mode.
This also adds unit tests to verify the APIs getSurroundSound and
setSurroundFormatEnabled.

Bug:171785330

Test: atest audiopolicy_tests
Test: Tested manually

Change-Id: Id309cc864fd380d7600c19e1839a63dd5756879f
diff --git a/services/audiopolicy/tests/AudioPolicyTestManager.h b/services/audiopolicy/tests/AudioPolicyTestManager.h
index 8bab020..be860e5 100644
--- a/services/audiopolicy/tests/AudioPolicyTestManager.h
+++ b/services/audiopolicy/tests/AudioPolicyTestManager.h
@@ -29,6 +29,7 @@
     using AudioPolicyManager::getOutputs;
     using AudioPolicyManager::getAvailableOutputDevices;
     using AudioPolicyManager::getAvailableInputDevices;
+    using AudioPolicyManager::setSurroundFormatEnabled;
     uint32_t getAudioPortGeneration() const { return mAudioPortGeneration; }
 };