feat(isBase64) #2491 #2573 Simplify isBase64 to prevent stack overflow

[KrayzeeKev]

Solves #2491 and #2573
Separate length check and then simplify regex to match any number of valid characters and 0 to 2 = on the end. Length check will ensure the {4} grouping is no longer necessary.

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable)
• Tests written (where applicable)
• References provided in PR (where applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (72573b3) to head (e947d6f).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2574   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          114       114           
  Lines         2535      2536    +1     
  Branches       641       642    +1     
=========================================
+ Hits          2535      2536    +1     

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[KrayzeeKev]

Who is able to provide additional approvals and get this published? We've got production issues as a result of this. Need to decide whether we downgrade or hold out.