feat(p/demo): PCG pseudo-random number generator #5239

Job	Run time
build (1.21.x, GOARCH=amd64 GOOS=linux, gno)	38s
build (1.21.x, GOARCH=wasm GOOS=js, gno)	30s
build (1.22.x, GOARCH=amd64 GOOS=linux, gno)	24s
build (1.22.x, GOARCH=wasm GOOS=js, gno)	26s
test (1.21.x, _test.cmd)	1m 28s
test (1.21.x, _test.pkg)	45s
test (1.21.x, _test.gnolang.native)	26s
test (1.21.x, _test.gnolang.stdlibs)	58s
test (1.21.x, _test.gnolang.realm)	37s
test (1.21.x, _test.gnolang.pkg0)	2m 0s
test (1.21.x, _test.gnolang.pkg1)	6m 26s
test (1.21.x, _test.gnolang.pkg2)	4m 22s
test (1.21.x, _test.gnolang.other)	24s
test (1.22.x, _test.cmd)	1m 37s
test (1.22.x, _test.pkg)	47s
test (1.22.x, _test.gnolang.native)	23s
test (1.22.x, _test.gnolang.stdlibs)	50s
test (1.22.x, _test.gnolang.realm)	49s
test (1.22.x, _test.gnolang.pkg0)	1m 49s
test (1.22.x, _test.gnolang.pkg1)	6m 22s
test (1.22.x, _test.gnolang.pkg2)	4m 3s
test (1.22.x, _test.gnolang.other)	31s
upload-coverage	11s
	36m 46s

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