feat: add 'gno env' subcommand #1595

Job	Run time
test (1.20.x, _test.flappy)	21s
build (1.20.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	11s
build (1.20.x, amd64, linux, ./pkg/amino/cmd/goscan)	11s
build (1.20.x, amd64, linux, ./pkg/autofile/cmd)	18s
test (1.20.x, _test.pkg.amino)	1m 25s
build (1.20.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	8s
test (1.20.x, _test.pkg.bft)	2m 25s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	11s
test (1.20.x, _test.pkg.others)	2m 36s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	13s
test (1.21.x, _test.flappy)	25s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	14s
test (1.21.x, _test.pkg.amino)	1m 24s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	10s
test (1.21.x, _test.pkg.bft)	2m 23s
test (1.21.x, _test.pkg.others)	2m 29s
upload-coverage	4s
	15m 8s

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