Add DeviceIdSet to AudioContainers

This CL adds a new container type for a set of device ids.
This is part of a larger change to add getRoutedDevices() functions.

Bug: 367816690
Test: make
Flag: android.media.audio.routed_device_ids
Change-Id: Id27fdbec9f259dfd86cc288cb58343d452048e4d
2 files changed