feat(catch-or-return): add `allowThenStrict` option

[brettz9]

What is the purpose of this pull request?

• [x] Changes an existing rule

What changes did you make? (Give an overview)

Added an allowThenStrict option which will fail on then(fn1, fn2) but pass on then(null, fn)

Also cleaned up the allowThen docs and tests.

Closes #52

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (bbcfcbf) to head (1a0161f). Report is 61 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #522   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           25        26    +1     
  Lines          649       699   +50     
  Branches       250       268   +18     
=========================================
+ Hits           649       699   +50     

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