chore: rename r/system -> r/sys #4750

Job	Run time
build (1.21.x, GOARCH=amd64 GOOS=linux, gno)	39s
build (1.21.x, GOARCH=wasm GOOS=js, gno)	13s
build (1.22.x, GOARCH=amd64 GOOS=linux, gno)	29s
test (1.21.x, _test.cmd)	1m 50s
build (1.22.x, GOARCH=wasm GOOS=js, gno)	25s
test (1.21.x, _test.pkg)	59s
test (1.21.x, _test.gnolang.native)	33s
test (1.21.x, _test.gnolang.stdlibs)	58s
test (1.21.x, _test.gnolang.realm)	42s
test (1.21.x, _test.gnolang.pkg0)	1m 58s
test (1.21.x, _test.gnolang.pkg1)	9m 56s
test (1.21.x, _test.gnolang.pkg2)	4m 14s
test (1.21.x, _test.gnolang.other)	38s
test (1.22.x, _test.cmd)	1m 31s
test (1.22.x, _test.pkg)	46s
test (1.22.x, _test.gnolang.native)	44s
test (1.22.x, _test.gnolang.stdlibs)	50s
test (1.22.x, _test.gnolang.realm)	40s
test (1.22.x, _test.gnolang.pkg0)	1m 49s
test (1.22.x, _test.gnolang.pkg1)	10m 4s
test (1.22.x, _test.gnolang.pkg2)	4m 5s
test (1.22.x, _test.gnolang.other)	26s
upload-coverage	14s
	44m 43s

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