Generate parser from `cwltool` extensions #963

Job	Run time
CI tests via Tox (3, 9, lint)	1s
CI linters via Tox (lint-readme)	22s
CI tests via Tox (3, 9, unit)	1s
CI linters via Tox (pydocstyle)	12s
CI tests via Tox (3, 9, bandit)	1s
CI tests via Tox (3, 9, mypy)	1s
cwl-utils release test	1m 52s
CI tests via Tox (3, 10, lint)	14s
CI tests via Tox (3, 10, unit)	17s
CI tests via Tox (3, 10, bandit)	24s
CI tests via Tox (3, 10, mypy)	18s
CI tests via Tox (3, 11, lint)	16s
CI tests via Tox (3, 11, unit)	17s
CI tests via Tox (3, 11, bandit)	22s
CI tests via Tox (3, 11, mypy)	17s
CI tests via Tox (3, 12, lint)	17s
CI tests via Tox (3, 12, unit)	16s
CI tests via Tox (3, 12, bandit)	25s
CI tests via Tox (3, 12, mypy)	17s
CI tests via Tox (3, 13, lint)	17s
CI tests via Tox (3, 13, unit)	17s
CI tests via Tox (3, 13, bandit)	17s
CI tests via Tox (3, 13, mypy)	18s
	7m 19s

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