Add handling of `.skip_lint` file(s) #225

Job	Run time
Setup as in CI for tools (3.11)	3m 59s
Setup as in PR for tools (3.11)	47s
Test testing of tools (0, 3.11)	3m 27s
Test testing of tools (1, 3.11)	3m 27s
Test linting of tools (3.11)	41s
Test testing of tools (2, 3.11)	3m 26s
Test combining 'chunked' test results (3.11)	45s
	16m 32s

Provide feedback