tree-sitter: introduce tree-sitter, add nix grammar #1449

Job	Run time
nix-build-develop-clang (none, release, true)	6m 8s
nix-build-develop-clang (none, release, false)	4m 27s
nix-build-develop-clang (none, debug, true)	3m 53s
nix-build-develop-clang (none, debug, false)	5m 19s
nix-build-develop-gcc (none, release, true)	5m 20s
nix-build-develop-gcc (none, release, false)	5m 40s
nix-build-develop-gcc (none, debug, true)	4m 25s
nix-build-develop-gcc (none, debug, false)	4m 29s
nix-build-develop-gcc (undefined, release, true)	10m 20s
nix-build-develop-gcc (undefined, release, false)	9m 42s
nix-build-develop-gcc (undefined, debug, true)	5m 31s
nix-build-develop-gcc (undefined, debug, false)	5m 19s
	1h 10m 33s

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