feat(vite-plugin-cloudflare): generate sourcemap for worker environments in build if upload_source_maps: true

[sushichan044]

issue: #11963

Still WIP, since not added tests and changesets yet

Describe your change...

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because:

A picture of a cute animal (not mandatory, but encouraged)

[changeset-bot]

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Latest commit: 718d57f

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