feat: get client IP from Context object rather than the request header

[ericapisani]

Originally the Edge function integrations were written under the assumption that we'd need to get the client IP from the request header.

However, the client IP is available in the Netlify Context object, so updating the adapter to reference that object rather than the request header.

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🦋 Changeset detected

Latest commit: 337dc79

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-netlify	Minor
@sveltejs/adapter-auto	Patch

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[Rich-Harris]

thank you!