Audio: Remove the concept of master volume.

- Remove two config resources (use master volume, and volume ramp).
- Remove master volume adjustments / getters / intents.
- Retain @hidden setMasterMute, needed for device admin
- Remove master volume logic in AudioService.
- Remove master volume logic in VolumePanel.
- Rename "getMasterStreamType" to "getUiSoundsStreamType" to avoid confusion.

Bug: 19582978
Change-Id: Id02c8fa4898cff3b913147f5ac1b4038e2e7cc24