add codespell action and correct spelling errors

[t-bltg]

• add gh action for codespell;
• correct spelling errors.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.54%. Comparing base (bb14fd5) to head (dc1db19).
Report is 1 commits behind head on v2.

Files with missing lines	Patch %	Lines
PlotsBase/src/layouts.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##               v2    #5011   +/-   ##
=======================================
  Coverage   86.54%   86.54%           
=======================================
  Files          51       51           
  Lines        5991     5991           
=======================================
  Hits         5185     5185           
  Misses        806      806           

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