Add extensions on `DateTime` and `List` #713

Job	Run time
health / breaking / run breaking health check	52s
health / changelog / run changelog health check	47s
health / license / run license health check	44s
health / version / run version health check	29s
health / coverage / run coverage health check	3m 12s
health / do-not-submit / run do-not-submit health check	47s
health / leaking / run leaking health check	53s
health / comment	8s
	7m 52s

Provide feedback