Add run_feature_selection to AutoMLSearch and Default Algorithm

[christopherbunn]

Resolves #4211

[codecov]

Codecov Report

Merging #4210 (f371945) into main (45d5ba3) will increase coverage by 0.1%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #4210     +/-   ##
=======================================
+ Coverage   99.7%   99.7%   +0.1%     
=======================================
  Files        349     349             
  Lines      38236   38256     +20     
=======================================
+ Hits       38116   38136     +20     
  Misses       120     120             

Impacted Files	Coverage Δ
...valml/automl/automl_algorithm/default_algorithm.py	99.7% <100.0%> (+0.1%)	⬆️
evalml/automl/automl_search.py	99.7% <100.0%> (+0.1%)	⬆️
...valml/tests/automl_tests/test_default_algorithm.py	100.0% <100.0%> (ø)

[jeremyliweishih]

LGTM - have a nit.