Godot FFI: postinit create, compat virtual methods, icon paths #3088

Job	Run time
doc-lints	41s
clippy	2m 6s
license-guard	31s
godot-itest (macos)	1m 6s
godot-itest (windows)	2m 14s
godot-itest (linux-full)	2m 7s
run-examples	1m 30s
rustfmt	7s
unit-test	2m 12s
godot-itest (linux-features-experimental)	1m 59s
godot-itest (linux-4.1)	1m 0s
godot-itest (linux-4.2)	55s
godot-itest (linux-memcheck)	2m 12s
ci-status	1s
	18m 41s

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