audio: Fix connection between alsa_device_profile and _proxy

alsa_device_proxy keeps a pointer to alsa_device_proxy,
but does not own it. Thus, the lifetime of the proxy must
be no less than of the proxy. In the legacy USB HAL impl
they were stored together (struct alsa_device_info).
Implement an equivalent class (DeviceProxy) in ALSA utils.

Bug: 264712385
Bug: 298712227
Test: atest VtsHalAudioCoreTargetTest
Change-Id: I4e36701752afb3f35664b6f2ad1acda5719be1ea