Create portability tag

[Bisaloo]

Fix #2867

cc @maelle

There is some overlap with the robustness tag, which made me realize that the robustness tag scope is not very clear (to me at least). Should I open a follow up issue for this?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.25%. Comparing base (77e258e) to head (ff2ae52).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3056   +/-   ##
=======================================
  Coverage   99.25%   99.25%           
=======================================
  Files         128      128           
  Lines        7368     7383   +15     
=======================================
+ Hits         7313     7328   +15     
  Misses         55       55           

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[MichaelChirico]

some more to consider: backport_linter(), paste_linter() (which has a rule around file.path()), system_file_linter(), pipe_consistency_linter() (which can be used to block native pipe)

I agree robustness is not perfectly defined, but seq_linter() is a good example that's appropriate for robustness but not portability. maybe we should just remove 'robustness' when what's meant is actually 'portability'?

[Bisaloo]

Can you imagine any case of a linter that would have both robustness and portability?