feat: clean up `gnokey add` + add coverage #4068

Job	Run time
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	9s
test (1.21.x, _test.flappy)	38s
test (1.21.x, _test.pkg.amino)	1m 41s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	6s
test (1.21.x, _test.pkg.bft)	2m 50s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	14s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	16s
test (1.21.x, _test.pkg.others)	1m 24s
test (1.22.x, _test.flappy)	31s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	16s
test (1.22.x, _test.pkg.amino)	1m 28s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/goscan)	11s
test (1.22.x, _test.pkg.bft)	2m 41s
build (1.22.x, amd64, linux, ./pkg/autofile/cmd)	14s
test (1.22.x, _test.pkg.others)	1m 30s
build (1.22.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	17s
upload-coverage	6s
	14m 32s

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