feat: add server property when load executes on server

[seo-rii]

• feat: expose server object
• test: add testcase
• chore: add changeset

Adds server property when load executes on server.
Closes #11828.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 9c6ea0e

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Minor

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14472-svelte.vercel.app/