Changes CoreStartable Dependencies to use Class.

The use of Class<CoreStartable> didn't work for cases where the root
class in the hierarchy which needs to be used as key didn't itself
extends CoreStartable, like in the next CL.

Bug: 332956676
Test: SysUIApplicationTest still passes
Test: manually verified that the crash in the bug no longer occurs after
the next CL
Flag: N/A

Change-Id: I98ad3af31b84e34a126486644ca77c5dcdbc471d