Add built-in support for web-workers

[marvinhagemeister]

This PR adds native support for Web Workers in WMR. It leverages native browser APIs and only requires the worker file to have .worker as a suffix in the filename.

Initially the plan was to use https://github.com/surma/rollup-plugin-off-main-thread instead, but that turned out tricky to wire up if we want to support bundling the worker by default. This is necessary because Firefox doesn't support module workers yet.

Fixes #825

[changeset-bot]

🦋 Changeset detected

Latest commit: 5f89737

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
wmr	Minor

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[github-actions]

Size Change: +597 B (0%)

Total Size: 806 kB

Filename	Size	Change
packages/wmr/wmr.cjs	767 kB	+597 B (0%)

ℹ️ View Unchanged

Filename	Size
examples/demo/dist/about/index.html	713 B
examples/demo/dist/alias-outside/index.html	692 B
examples/demo/dist/assets/Calendar.********.css	702 B
examples/demo/dist/assets/style.********.css	624 B
examples/demo/dist/chunks/alias-outside.********.js	138 B
examples/demo/dist/chunks/class-fields.********.js	211 B
examples/demo/dist/chunks/compat.********.js	15.3 kB
examples/demo/dist/chunks/hoofd.module.********.js	1.48 kB
examples/demo/dist/chunks/index.********.js	303 B
examples/demo/dist/chunks/json.********.js	238 B
examples/demo/dist/chunks/meta-tags.********.js	297 B
examples/demo/dist/chunks/prerender.********.js	2.43 kB
examples/demo/dist/class-fields/index.html	703 B
examples/demo/dist/compat/index.html	1.55 kB
examples/demo/dist/env/index.html	779 B
examples/demo/dist/error/index.html	708 B
examples/demo/dist/files/index.html	741 B
examples/demo/dist/index.********.js	7.69 kB
examples/demo/dist/index.html	770 B
examples/demo/dist/json/index.html	711 B
examples/demo/dist/lazy-and-late/index.html	714 B
examples/demo/dist/meta-tags/index.html	782 B

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