feat(stdlibs): add package `strconv` #5338

Job	Run time
setup	6s
Run Main (gnodev) / Go Build / generated	16s
Run Main (gnodev) / Go Linter / lint	48s
Run Main (gnofaucet) / Go Linter / lint	29s
Run Main (gnofaucet) / Go Build / generated	10s
Run Main (gnodev) / Go Test / test	1m 11s
Run Main (gnofaucet) / Go Test / test	36s
Run Main (gnokeykc) / Go Linter / lint	35s
Run Main (gnokeykc) / Go Build / generated	9s
Run Main (gnokeykc) / Go Test / test	41s
Run Main (gnomd) / Go Build / generated	6s
Run Main (gnomd) / Go Linter / lint	20s
Run Main (gnomd) / Go Test / test	29s
	5m 56s

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