Revert "refactor: plugin platform code cleanup"

[jhockett]

Reverts #10384

Breaks pkg CLI build: https://app.circleci.com/pipelines/github/aws-amplify/amplify-cli/8459/workflows/4d90aab3-f292-4f60-9b0a-0deacbc40f4e/jobs/251296

[alharris-at]

Successful run w/ revert https://app.circleci.com/pipelines/github/aws-amplify/amplify-cli/8465/workflows/1937156b-a95f-4345-a26c-e2dc18bd029f/jobs/251332

[codecov-commenter]

Codecov Report

Merging #10403 (92292b5) into master (2612585) will decrease coverage by 0.00%.
The diff coverage is 59.52%.

@@            Coverage Diff             @@
##           master   #10403      +/-   ##
==========================================
- Coverage   46.57%   46.57%   -0.01%     
==========================================
  Files         703      703              
  Lines       35245    35254       +9     
  Branches     7136     7137       +1     
==========================================
+ Hits        16417    16418       +1     
- Misses      17043    17049       +6     
- Partials     1785     1787       +2     

Impacted Files	Coverage Δ
...ify-cli/src/plugin-helpers/scan-plugin-platform.ts	17.85% <34.21%> (-3.25%)	⬇️
packages/amplify-cli/src/plugin-manager.ts	17.39% <67.85%> (-0.26%)	⬇️
...es/amplify-cli/src/plugin-helpers/verify-plugin.ts	100.00% <100.00%> (ø)

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