feat: atomic builds

[magnusdahlstrand]

Before this PR, when building adapter-cloudflare first removes the build directory, then initiates a build.

When using workers-sdk alongside sveltekit this leads to lots of error messages when watching and rebuilding, first due to files not existing, and then due to incomplete builds. This creates lots of output of transient errors in the console confusing the development process (especially for beginners), and also hides any real issues behind a wall of non-errors.

This PR updates the build behaviour to leave the existing build in place while building to a new temporary build location. When the build finishes, the final build destination is removed and the temporary build directory is renamed to take the place of the final build destination.

This fixes all of the transient error outputs during rebuilds. I'm working on fixes to workers-sdk as well which should further smooth the integration between these two projects.

Let me know if you have any questions or feedback, I'm all ears!

Magnus

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🦋 Changeset detected

Latest commit: 84443d4

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

This PR includes changesets to release 2 packages

Name	Type
@sveltejs/adapter-cloudflare	Minor
@sveltejs/adapter-cloudflare-workers	Minor

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[benmccann]

It feels to me like we'd want to make this change to the cloudflare-workers-adapter as well

[eltigerchino]

I've added similar changes to the cloudflare workers adapter.

[eltigerchino]

I think this may be a patch fix instead; it prevents those transient error messages during rebuilds.