add requires_utf8 argument to tests

[ben-schwen]

Closes #7336
Closes #1343
Closes #7333

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.13%. Comparing base (8ab0b2b) to head (fa5967f).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7388   +/-   ##
=======================================
  Coverage   99.13%   99.13%           
=======================================
  Files          85       85           
  Lines       16577    16600   +23     
=======================================
+ Hits        16433    16456   +23     
  Misses        144      144           

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[github-actions]

• HEAD=tests_requires_utf8 stopped early for DT[by,verbose=TRUE] improved in #6296
• HEAD=tests_requires_utf8 slower P<0.001 for setDT improved in #5427
  

Generated via commit fa5967f

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

Task	Duration
R setup and installing dependencies	2 minutes and 44 seconds
Installing different package versions	21 seconds
Running and plotting the test cases	2 minutes and 53 seconds

[aitap]

Sorry if I'm late to note this, but wouldn't a more reliable test for this be the same thing as we currently use for ñ in test 2266? A test may require some symbols (ñ, ü, ん) to be representable in the native encoding. The symbols may be represented using Unicode escapes (\uXXXX) as they currently do. If !identical(foo, enc2native(foo)), then the test must be skipped.

[ben-schwen]

The symbols may be represented using Unicode escapes (\uXXXX) as they currently do. If !identical(foo, enc2native(foo)), then the test must be skipped.

Good point. I have integrated this for the utf8_check.