Add string support for data check action code

[bchen1116]

fix #1904

[codecov]

Codecov Report

Merging #3167 (5cb62d4) into main (2b7c4a8) will increase coverage by 0.1%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #3167     +/-   ##
=======================================
+ Coverage   99.7%   99.7%   +0.1%     
=======================================
  Files        320     322      +2     
  Lines      31029   31070     +41     
=======================================
+ Hits       30924   30965     +41     
  Misses       105     105             

Impacted Files	Coverage Δ
evalml/data_checks/data_check_action.py	100.0% <100.0%> (ø)
evalml/data_checks/data_check_action_code.py	100.0% <100.0%> (ø)
evalml/data_checks/utils.py	100.0% <100.0%> (ø)
.../tests/data_checks_tests/test_data_check_action.py	100.0% <100.0%> (ø)
evalml/tests/data_checks_tests/test_utils.py	100.0% <100.0%> (ø)

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[angela97lin]

LGTM, thank you for taking this on! 🙏 Just left a few really nit-picky comments :)

[jeremyliweishih]

noice!