Add broadcast feature supported API

Expose isLeAudioBroadcastSourceSupported and isLeAudioBroadcastAssistantSupported
API. It would check the controller capabilities for now, and plan to
check the profile enable status later.

Bug: 150670922
Bug: 208368819
Test: make build
Change-Id: Ic68a19575e09dc8cf525c28afaca92ea44158981
Merged-In: Ic68a19575e09dc8cf525c28afaca92ea44158981