Add `is_intent` kwarg to MycroftSkill class to resolve errors #468

Job	Run time
unit_tests (3.7)	1m 7s
unit_tests (3.8)	1m 12s
unit_tests (3.9)	1m 17s
unit_tests (3.10)	1m 21s
unit_tests (3.11)	1m 13s
py_build_tests / py_build_tests	9s
py_build_tests / relative_path_tests	6s
	6m 25s

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