fix(rollup): generated JS always uses clean names

[tivac]

Description

Adding in an extra layer of tracking of renamed/uniqued variables so that they're always used instead of raw classnames, for instances where that isn't a valid JS identifier that can be safely exported/imported.

Motivation and Context

Fixes #846

How Has This Been Tested?

Wrote tests for it.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• [] My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

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[codecov]

Codecov Report

Merging #847 (7ffd39c) into main (39ab577) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 7ffd39c differs from pull request most recent head f2b5e73. Consider uploading reports for the commit f2b5e73 to get more accurate results

@@           Coverage Diff           @@
##             main     #847   +/-   ##
=======================================
  Coverage   99.58%   99.58%           
=======================================
  Files          37       37           
  Lines        1435     1439    +4     
  Branches      232      232           
=======================================
+ Hits         1429     1433    +4     
  Misses          6        6           

Impacted Files	Coverage Δ
packages/css-to-js/css-to-js.js	100.00% <100.00%> (ø)

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