Add support for filename-pattern on ns-group

[ericdallo]

Fixes #1790

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• This PR corresponds to an issue with a clear problem statement.

• This PR contains a test to prevent against future regressions

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[borkdude]

Looks good, I wonder if this works on Windows too using the same regex.

[ericdallo]

@borkdude good catch, maybe I can simplify the regex in the test

[borkdude]

Isn't that just hiding the problem? I think those regexes should work for *nix and Windows, else you would have to write some pretty hairy regexes to target both. We already have similar regexes for :output {:exclude-file ...}.

[borkdude]

Hmm, since we don't have support for this in :exclude-files either, we will address that when necessary. So this PR is sufficient imo.