Introduce SchedulingStateMachine for unified scheduler [NO-MERGE&REVIEW-ONLY-MODE] #11212

Job	Run time
android (ubuntu-20.04, x86_64-linux-android)	2m 49s
android (ubuntu-20.04, aarch64-linux-android)	3m 1s
ios (macos-11, aarch64-apple-ios)	6m 12s
android (ubuntu-20.04, i686-linux-android)	3m 10s
ios (macos-11, x86_64-apple-ios)	8m 3s
android (ubuntu-20.04, armv7-linux-androideabi)	3m 15s
ios (macos-11, aarch64-apple-darwin)	6m 45s
ios (macos-11, x86_64-apple-darwin)	9m 33s
error_reporting	0s
	42m 48s

Provide feedback