Updated excluded_model_families data type

[remyogasawara]

Resolves #4259

Updated excluded_model_families to allow both str and ModelFamily data types and updated corresponding documentation.

[codecov]

Codecov Report

Patch coverage: 100.0% and project coverage change: +0.1% 🎉

Comparison is base (ecbb2e4) 99.7% compared to head (2ccf674) 99.7%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #4287     +/-   ##
=======================================
+ Coverage   99.7%   99.7%   +0.1%     
=======================================
  Files        355     355             
  Lines      39154   39155      +1     
=======================================
+ Hits       39034   39035      +1     
  Misses       120     120             

Files Changed	Coverage Δ
...valml/automl/automl_algorithm/default_algorithm.py	99.7% <ø> (ø)
...lml/automl/automl_algorithm/iterative_algorithm.py	97.5% <ø> (ø)
evalml/pipelines/components/utils.py	96.8% <ø> (ø)
evalml/automl/automl_search.py	99.8% <100.0%> (ø)
evalml/tests/automl_tests/test_automl.py	99.5% <100.0%> (+0.1%)	⬆️

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jeremyliweishih]

Let's also assert than any linear models are not created as well.

[eccabay]

Thank you!