Rename SMOTE samplers to SMOTE oversampler

[angela97lin]

Reviving some work in #2210:

• Rename OverSampler --> Oversampler
• Add "Over" to all of the SMOTE sampler classes, ex: SMOTESampler --> SMOTEOversampler

[codecov]

Codecov Report

Merging #2595 (e36935a) into main (2b56388) will not change coverage.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main   #2595   +/-   ##
=====================================
  Coverage   99.9%   99.9%           
=====================================
  Files        295     295           
  Lines      27063   27063           
=====================================
  Hits       27017   27017           
  Misses        46      46           

Impacted Files	Coverage Δ
evalml/pipelines/components/__init__.py	100.0% <ø> (ø)
evalml/pipelines/utils.py	99.2% <ø> (ø)
...alml/pipelines/components/transformers/__init__.py	100.0% <100.0%> (ø)
...lines/components/transformers/samplers/__init__.py	100.0% <100.0%> (ø)
...s/components/transformers/samplers/base_sampler.py	100.0% <100.0%> (ø)
...s/components/transformers/samplers/oversamplers.py	100.0% <100.0%> (ø)
evalml/tests/component_tests/test_components.py	100.0% <100.0%> (ø)
evalml/tests/component_tests/test_oversamplers.py	100.0% <100.0%> (ø)

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[bchen1116]

LGTM!