Add support for content layer in env API

[ascorbic]

Changes

Adds support for content layer in workerd with env api. It's basically just removing a couple of type guards that are no longer needed that were disabling the watchers, and most of the PR is copying over the content layer fixture into the Vite plugin cf fixture

Testing

Docs

[changeset-bot]

⚠️ No Changeset found

Latest commit: c893c5e

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR