Pass-by-ref for non-`Copy` builtins (frontend) #2823

Job	Run time
license-guard	29s
doc-lints	55s
clippy	1m 43s
godot-itest (macos)	1m 6s
run-examples	1m 27s
rustfmt	26s
godot-itest (windows)	3m 25s
unit-test	2m 28s
godot-itest (linux-full)	2m 35s
godot-itest (linux-features-experimental)	1m 56s
godot-itest (linux-4.1)	1m 16s
godot-itest (linux-4.2)	1m 14s
godot-itest (linux-memcheck)	2m 9s
ci-status	3s
	21m 12s

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