chore(example): migrate to `react-native-test-app` #437

Job	Run time
Install dependencies	7s
Verify example app sources	39s
Lint the sources	12s
Run the unit tests	11s
Build example app iOS	0s
Build example app Android	0s
Build example app Windows	0s
Build example app iOS (Fabric)	0s
Build example app Android (Fabric)	0s
	1m 9s

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