Add the possibility to provide the list of tools as file

[bernt-matthias]

trafficstars

e.g. for test, *lint, shed_lint and, workflow_lint, workflow_test :

this would often simplify the CI code:

• https://github.com/galaxyproject/galaxy/pull/12104#discussion_r650074197
• https://github.com/galaxyproject/planemo-ci-action/blob/80d6ba560a2847391493542116edf3c66f95f0cb/planemo_ci_actions.sh#L77
• https://github.com/galaxyproject/planemo-ci-action/blob/80d6ba560a2847391493542116edf3c66f95f0cb/planemo_ci_actions.sh#L105