Constrain `State: Equatable` in `TestStore` #6204

Job	Run time
Library (evolution)	4m 2s
xcodebuild (16) (test, IOS, 16.0)	8m 9s
Examples	17m 46s
xcodebuild (16) (test, MACOS, 16.0)	2m 38s
xcodebuild (15) (test, IOS, 15.4)	36m 31s
xcodebuild (16) (IOS, 16.0)	4m 2s
Check Macro Compatibility	3m 33s
xcodebuild (15) (test, MAC_CATALYST, 15.4)	5m 49s
xcodebuild (16) (MACOS, 16.0)	1m 30s
xcodebuild (15) (test, MACOS, 15.4)	3m 16s
xcodebuild (15) (test, TVOS, 15.4)	20m 29s
xcodebuild (15) (test, VISIONOS, 15.4)	38m 59s
xcodebuild (15) (test, WATCHOS, 15.4)	31m 5s
xcodebuild (15) (IOS, 15.2)	10m 50s
xcodebuild (15) (MACOS, 15.2)	2m 42s
	3h 11m 21s

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