Support more locales in R-CMD-check-occasional

[MichaelChirico]

As surfaced during review, lv_LV is not quite enough to catch all possible collation issues.

Since this CI is only run "rarely", combinatorial explosion of settings is not so big a concern.

[github-actions]

• HEAD=occasional-more-locales much slower for transform improved in #5493
• HEAD=occasional-more-locales slower P<0.001 for DT[by] max regression fixed in #7480
  

Generated via commit ef77a1e

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	6 minutes and 26 seconds
Installing different package versions	12 minutes and 38 seconds
Running and plotting the test cases	5 minutes and 33 seconds

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.01%. Comparing base (58dbcdd) to head (ecab787).

Additional details and impacted files

@@             Coverage Diff              @@
##           tests-azeri    #7869   +/-   ##
============================================
  Coverage        99.01%   99.01%           
============================================
  Files               88       88           
  Lines            17292    17292           
============================================
  Hits             17122    17122           
  Misses             170      170           

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[MichaelChirico]

At least partly this is blocked by an upstream error that {R.oo} can't install in az_AZ:

HenrikBengtsson/R.oo#31

[aitap]

Interesting. I've tried test.data.table() in all locales again (setting LC_ALL but also LANGUAGE=en; otherwise the failures are inconvenient to parse and many of those are probably due to R being translated while data.table is not) and the only remaining failures are tests 168.[1-3] in locales bo_CN, bo_IN, dz_BT, km_KH, shn_MM, tok, vi_VN: this is due to R bug 19117. Are the tests supposed to be still failing in CI?