New resources for ambient volume icons

The main icon is ic_ambient_volume. It's a level-list drawable which has
25 different levels to represent different level of left and right
ambient volume.

Flag: com.android.settingslib.flags.hearing_devices_ambient_volume_control
Bug: 357878944
Test: build pass
Change-Id: I15d00cfb59f631084b93d8bf35571e2fc054faa7