WebSocket proxy should be backed by an actual `ChunkStore`

[teh-cmc]

Currently the proxy just drops older data as memory becomes scarce.

It should instead instantiate an actual store with proper garbage collection so that static data always sticks around.

Would also probably fix:

• New clients do not receive data in Web-Viewer mode after dropping old messages #5344

[slyfox3]

While we are on this, can we add also a new option to connect() to only receive static + future data, but not older data?

[teh-cmc]

While we are on this, can we add also a new option to connect() to only receive static + future data, but not older data?

Once the proxy is backed by an actual ChunkStore, that would be fairly trivial to implement yes.

[teh-cmc]

This has been a common user-request, coming in in many different forms, the last few months.

Slapping a user-request on it, and slowly creeping it into plannings.