[WIP] Add Multiplayer Example #2851

Job	Run time
doc-lints	47s
clippy	1m 54s
license-guard	33s
godot-itest (macos)	1m 0s
run-examples	1m 13s
godot-itest (windows)	3m 12s
rustfmt	13s
unit-test	2m 29s
godot-itest (linux-full)	2m 28s
godot-itest (linux-features-experimental)	1m 3s
godot-itest (linux-4.1)	1m 18s
godot-itest (linux-4.2)	1m 19s
godot-itest (linux-memcheck)	2m 18s
ci-status	2s
	19m 49s

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