Add methods for suggested devices called from UMO

Add methods to connect to a suggested device, and also refactor code
around determining the icon for the device type so UMO can surface the
proper icon.

Flag: com.android.media.flags.enable_suggested_device_api
Test: atest
Bug: 393216614
Change-Id: I1da4bc84eb5986287cdef703d7cf69c0e4b1ab68