LE Audio: Expose more system APIs

* Expose two intentss:
  * ACTION_LE_AUDIO_ACTIVE_DEVICE_CHANGED
  * ACTION_LE_AUDIO_GROUP_NODE_STATUS_CHANGED
  * Settings and Telecom are interested in the group node status
    information, therefore lets expose the API as a SystemApi
* Reduce scope of HAP connection state API to system API
* Expose more system APIs for HAP client
  * To select different hearing presets
  * To get notified about changes in hearing presets
  * To get all available hearing presets
* Expose more system APIs for CSIP
  * To make error codes more visible for the API caller
* Expose GROUP_ID_INVALID to public API for getGroupId()

Bug: 150670922
Test: atest BluetoothInstrumentationTests
Tag: #feature
Sponsor: siyuanh@
Ignore-AOSP-First: earlier change merged on internal
Change-Id: If87e0863f23b989632603ac1253e4a77bfff028d
Merged-In: If87e0863f23b989632603ac1253e4a77bfff028d
(cherry picked from commit a89f2e1a)