Introduce SchedulingStateMachine for unified scheduler [NO-MERGE&REVIEW-ONLY-MODE] #11170

Job	Run time
android (ubuntu-20.04, x86_64-linux-android)	2m 56s
android (ubuntu-20.04, aarch64-linux-android)	2m 58s
android (ubuntu-20.04, i686-linux-android)	3m 2s
android (ubuntu-20.04, armv7-linux-androideabi)	3m 20s
ios (macos-11, aarch64-apple-ios)	7m 0s
ios (macos-11, x86_64-apple-ios)	6m 28s
ios (macos-11, aarch64-apple-darwin)	7m 20s
ios (macos-11, x86_64-apple-darwin)	7m 11s
error_reporting	0s
	40m 15s

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