le_audio: Differentiate Broadcast and Unicast for ClientInterface

While Broadcast and Unicast Sink Client Interface Endpoints can be
instantiated simultanousely a spearate Cleanup procedure should be
performed. Also Broadcast and Unicast transports should not share common
status.

Tag: #feature
Bug: 299238288
Test: atest BluetoothInstrumentationTests
Change-Id: I1f86e2b08a56a612e9c0f8a63f7c4c84916e59db