feat: add support for Netlify Edge Functions

[ascorbic]

This PR adds support for the beta release of Netlify Edge Functions to the Netlify adapter. It adds an option edge to the adapter, which if set to true, compiles an edge function that runs on the Deno runtime as well as an edge functions manifest, instead of the Node-based Netlify Function.

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🦋 Changeset detected

Latest commit: 88a12d4

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

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Name	Type
@sveltejs/adapter-netlify	Patch

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[Rich-Harris]

Thanks, and congrats on the launch! I made a small tweak to the README (the GitHub UI didn't let me use the suggestion tool, since the diff had both red and green, but our convention is to document all the available options in the code sample), and added an inline comment about handling edge: true alongside split: true

[Rich-Harris]

thank you!

[Masstronaut]

@ascorbic thrilled to see you implemented this!