Update layer availability when publishers are disconnected.

Implement VmsPublisherService proxy to handle connection cleanup.
Block calls to proxied VmsPublisherService after client disconnect.
Move HAL service connection handling to VmsClientManager.
Notify client listeners of connected clients when registering.

Bug: 123094085
Test: Manual testing of VMS integration on reference platform
Test: atest AndroidCarApiTest CarServiceTest CarServiceUnitTest
Change-Id: I42de0bfd9f54df76039f9b4b4f004a745762c605
6 files changed