chore: add empty test files for consistent coverage (#1147) #1

Job	Run time
test (1.20.x, _test.flappy)	1m 0s
build (1.20.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	14s
test (1.20.x, _test.pkg.amino)	4m 57s
build (1.20.x, amd64, linux, ./pkg/amino/cmd/goscan)	16s
test (1.20.x, _test.pkg.bft)	4m 39s
build (1.20.x, amd64, linux, ./pkg/autofile/cmd)	22s
test (1.20.x, _test.pkg.others)	5m 31s
build (1.20.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	24s
test (1.21.x, _test.flappy)	1m 4s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	18s
test (1.21.x, _test.pkg.amino)	3m 45s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	14s
test (1.21.x, _test.pkg.bft)	4m 41s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	23s
test (1.21.x, _test.pkg.others)	8m 14s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	30s
	36m 32s

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