tree-sitter: rewrite comment grammar, detach line- and block comments #160

Job	Run time
build (ubuntu-20.04, debug)	35s
build (ubuntu-20.04, dev)	26s
build (ubuntu-20.04, release)	1m 27s
build (macos-latest, debug)	1m 7s
build (macos-latest, dev)	1m 47s
build (macos-latest, release)	3m 3s
build (windows-latest, debug)	2m 23s
build (windows-latest, dev)	2m 22s
build (windows-latest, release)	3m 16s
	16m 26s

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