Minor performance improvements

[richardscull]

Docker related fixes/improvements:

• Add Sunrise.Processing to Dockerfile
• Limit sunrise docker compose memory

I'm going to test sunrise memory limit configuration for some time on the production, hopefully it is pretty reasonable.

Improvements:

• Improve websocket memory clean up
• Add isFinished and Timer dispose invocation for MultiplayerTimer
• Use single HttpClient for the HttpClientService with memory disposal
• Remove abstract channels by key from ChatChannelRepository
• On soft session removal remove all spectators and remove itself from multiplayer lobby

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