Add Support for Fresh-like Islands

[INTERNAL-ERROR]

Describe the problem

Currently Svelte has support for page-wide options for prerendering and hydrating, like so:

<script context="module"> export const prerender = true; </script>

But, as I was listening to a podcast from JSParty about Fresh, I heard them talking about Island architecture. What if we could use these options for prerendering and hydrating specifically for components? This would allow you to create prerendered segments of Svelte components. This allows for greater control over how you render your page, and would allow for you to make a site completely without javascript except for a specific piece of the website/

Describe the proposed solution

Allow you to use

<script context="module"> export const prerender = true; </script>

Plus other page options, such as hydrate.

Alternatives considered

Feel free to suggest alternatives.

Importance

nice to have

Additional Information

Great article explaining Islands here:
Again, not sure if there is a Sveltekit way to do this - just wanted to see if this would work for component.

[dummdidumm]

Closely related to #1390

[Rich-Harris]

Going to close this as it's too broad an issue to act upon. We may add some sort of partial hydration mechanism in the future if it feels like the right approach, but it likely wouldn't be islands (which is really only suitable for a narrow subset of web apps, and is far from the optimal approach for partial hydration; it's mainly popular because it's an easy approach to build a framework around).