Kani

Add harnesses for safety of primitive conversions #1244

Job	Run time
Kani List	11m 48s
Verify std library (partition 1)	39m 43s
Verify std library (partition 2)	42m 27s
Verify std library (partition 3)	35m 54s
Verify std library (partition 4)	52m 19s
Verify std library (partition 1)	30m 40s
Verify std library (partition 2)	34m 54s
Verify std library (partition 3)	36m 7s
Verify std library (partition 4)	38m 31s
	5h 22m 23s

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