refactor: Convert more Taxonomy code to TypeScript

[bradenmacdonald]

Description

1. Converts some files from .js or .mjs to .ts
2. Moves the API code from src/taxonomy/tag-list/data into src/taxonomy/data
3. Cleans up and improves some type definitions

No user-visible changes / functionality changes.

This is just a first step. I will follow with more PRs. I'm trying to keep each PR small so they're easier to review.

Testing instructions

Ensure no regressions.

Other information

Private ref: MNG-4479

[openedx-webhooks]

Thanks for the pull request, @bradenmacdonald!

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[ChrisChV]

Looks good 👍

• I tested this: I have tested the screens involved
• I read through the code and considered the security, stability and performance implications of the changes.
• I tested that the UI can be used with a keyboard only (tab order, keyboard controls).

[bradenmacdonald]

Thanks @ChrisChV !