fix(eslint-plugin): [prefer-regexp-exec] respect flags when using RegExp

[rafaelss95]

Fixes #3477.

[typescript-eslint]

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[codecov]

Codecov Report

Merging #3855 (1453074) into master (4195919) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 1453074 differs from pull request most recent head 9fa7537. Consider uploading reports for the commit 9fa7537 to get more accurate results

@@           Coverage Diff           @@
##           master    #3855   +/-   ##
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  Coverage   93.50%   93.51%           
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  Files         151      151           
  Lines        8134     8140    +6     
  Branches     2580     2583    +3     
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+ Hits         7606     7612    +6     
  Misses        167      167           
  Partials      361      361           

Flag	Coverage Δ
unittest	93.51% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
...ages/eslint-plugin/src/rules/prefer-regexp-exec.ts	100.00% <100.00%> (ø)

[bradzacher]

It looks like there currently aren't any existing tests for new RegExp - but I just checked and the rule currently supports its.
It just doesn't do the "global" check on them.

Your change causes the new RegExp constructor to be completely ignored - which is not correct.

Instead we should inspect the new constructor to extract the second argument to determine if it has a 'g' in the string

[rafaelss95]

Your change causes the new RegExp constructor to be completely ignored - which is not correct.

@bradzacher Sorry, but I didn't understand what you mean, I've tested it locally and the reports went expected. Note that I had already added a test that covered new RegExp(...) for valid cases and I just added another one for invalid ones, just in case.

Oh, wait, I see... there's some inconsistent behavior. I'll look ASAP.

[bradzacher]

thanks for adding all of those tests!
LGTM!