Protocol Buffers as network protocol for Freeciv-web

[andreasrosdal]

https://protobuf.dev/

Steps: 1: Convert packets.def to freeciv.proto in the protobuf format. https://github.com/freeciv/freeciv/blob/main/common/networking/packets.def

See freeciv.proto here generated by OpenAI: freeciv_generated_final.proto.txt

2: Update Freeciv-web to use the Protocol Buffers format.

3: Update Freeciv C server to use Protocol Buffers.

4.: Remove freeciv-proxy.

5: Use libwebsocket in the Freeciv C server.