Target signals to specific clients

[ryanbliss]

• Added ability to send signals to specific clients, for drivers that support it (e.g., odsp-driver).
• Once azure-client and tinylicious supports targetClientId at service level, this will work automatically.
• For unsupported drivers, the behavior is simulated appropriately such that events are only handled from the targeted client.
• Updated LiveEvent and useLiveEvent to support optional targeting, and updated sample 04 with an example.
• Implement targeting out of box for LiveObjectSynchronizer and LiveMediaSessionCoordinator connect events out of the box. For supported drivers, this will decrease COGS and server load considerably in larger session sizes (no N^2).

Non-targeted behavior (existing):
This is the behavior when no targetClientId is provided. All remote clients will receive the event.

Target client behavior:
This is the behavior when targetClientId is provided (left side is targeting top-right). Notice how the top-right received the most recent message sent by the top-left.

[huntj88]

Looks good, would add a couple unit tests

[ryanbliss]

Looks good, would add a couple unit tests

Added UTs to LiveEvent and LiveObjectSynchronizer, which should give us more or less complete coverage for the scenarios at hand.