floss: Add IsLEAudioStable API

Add new API that returns true for a remote device if its model
is in the allowlist. The allowlist is stored as sysprop
persist.bluetooth.leaudio.allow_list. Add handling for getting
this sysprop in Rust. Also add RemoteModelName property in
btif to get the remote device's model name.

Bug: 341977695
Tag: #floss
Test: btclient - device info <Samsung Galaxy Pro Buds2>
Test: mmm packages/modules/Bluetooth
Flag: EXEMPT, floss change for ChromeOS only
Change-Id: Iafe55d86a0cd67ad20214b9c534fc4bd2420d0e7