Dev idea: GH annotator action at line level of PRs with outputs

[yarikoptic]

Inspired by https://github.com/codespell-project/codespell-problem-matcher which is based on https://github.com/korelstar/xmllint-problem-matcher which leads me to description of the overall feature of GH actions to annotate lines based on matching regex in output of the action: https://github.com/actions/toolkit/blob/main/docs/problem-matchers.md .

It is very handy to see in PRs annotations on the lines which lead to some CI failures/warnings. And if we are to add some generalized validation structure/output - we could have a generic matcher/annotator to pin point to specific files/lines in the results of validation (e.g. for BIDS datasets etc)

• is limited in number of annotations possible to provide. So for "mass ones", only first hit + may be referencing of other hits
• wouldn't be super useful for validation within binary files I guess since structure is not visualized
• ...

ping'ing @effigies @VisLab @tgbus to get initial feedback on the idea