Harden multiplayer networking and adapt frame timing

[ZivDero]

Reworks thbe networking:

1. Hardens network packet handling
   Defended against too small, too large packets, malformed packets, unknown packets.
   Also covers the entire abuse set of sending packets as another player's house, so now the only way to cheat here is to fake stuff on the actual network transport layer.

2. Improve connection-level timing
   Partly based on Add fast retransmit of lost packets and packet redundancy CnCNet/yrpp-spawner#75
   Improves actual connection timing to better reflect connection quality on a per-connection basis to not stall everyone unnecessarily.

3. Improve lockstep timing
   An evolution of "protocol zero", improving the selection of FrameSendRate and MaxAhead based on the connection quality.
   Includes downgrading for bad connections and limited upgrading (to prevent ping-pong when connection quality varies).

Closes #21, closes #22, closes #23, closes #24, closes #25, closes #26, closes #35

[github-actions]

Development builds of 4230f5a:

• opents-Release-c66fff8
• opents-Debug-c66fff8

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