Refactor - Demotes `Arc` to `Rc`. #7808

Job	Run time
ios (macos-11, aarch64-apple-ios)	9m 4s
ios (macos-11, x86_64-apple-ios)	8m 26s
ios (macos-11, aarch64-apple-darwin)	8m 28s
ios (macos-11, x86_64-apple-darwin)	8m 55s
android (ubuntu-20.04, x86_64-linux-android)	8m 49s
android (ubuntu-20.04, aarch64-linux-android)	8m 52s
android (ubuntu-20.04, i686-linux-android)	9m 54s
android (ubuntu-20.04, armv7-linux-androideabi)	9m 23s
error_reporting	0s
	1h 11m 51s

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