Replace Jest with Vitest 2

[birkskyum]

This PR replaces the test runner (unit/integration/build) from Jest to Vitest 2, which has built-in support for TS/ESM and the same syntax as Jest. This PR serves to help us evaluate the option, and to move forward faster if there's a decision to proceed at some point.

A key motivation for examining this change is that I've found it quite challenging to move these tickets forward:

• ECMAScript Modules #1595
• Tree shaking #977

Part of the struggle is that Jest only has experimental ESM support, and I've so far not managed to see an effect of the useESM setting in the ts-jest plugin used in this repo.

It's a continuation of

• Use platform consistently instead of jest done #4684

Relates to Rolldown, because vitest is downstream of vite, and thus eventually will swap internals to use rolldown:

• Future: Move bundling from Rollup to Rolldown #4669

Relates a bit to browser runner, because vitest is working on a browser mode:

• Future: Replace Puppeteer with Playwright #4949

Launch Checklist

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 71.14%. Comparing base (d3f2bca) to head (28ec0ae).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/source/tile.ts	0.00%	0 Missing and 1 partial ⚠️
src/util/web_worker_transfer.ts	0.00%	0 Missing and 1 partial ⚠️

❗ There is a different number of reports uploaded between BASE (d3f2bca) and HEAD (28ec0ae). Click for more details.

HEAD has 3 uploads less than BASE

Flag	BASE (d3f2bca)	HEAD (28ec0ae)
	9	6

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #4728       +/-   ##
===========================================
- Coverage   90.48%   71.14%   -19.34%     
===========================================
  Files         265      262        -3     
  Lines       38113    37819      -294     
  Branches     3166     1955     -1211     
===========================================
- Hits        34488    26908     -7580     
- Misses       2650     9638     +6988     
- Partials      975     1273      +298     

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