feat(p/demo): PCG pseudo-random number generator #4303

Job	Run time
test (1.21.x, _test.flappy)	38s
test (1.21.x, _test.pkg.amino)	1m 38s
test (1.21.x, _test.pkg.bft)	2m 31s
test (1.21.x, _test.pkg.others)	1m 24s
test (1.22.x, _test.flappy)	28s
test (1.22.x, _test.pkg.amino)	1m 31s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	12s
test (1.22.x, _test.pkg.bft)	2m 20s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	5s
test (1.22.x, _test.pkg.others)	1m 17s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	16s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	9s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	8s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/goscan)	10s
build (1.22.x, amd64, linux, ./pkg/autofile/cmd)	7s
build (1.22.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	19s
upload-coverage	9s
	13m 22s

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