feat: allow let props = $props(), optimize prop read access

[dummdidumm]

• allow to write let props = $props() (helps with some use cases of Add a (singular) $prop rune #9241)
• optimize read access of props.x to use $$props argument directly; closes Svelte 5: optimise prop access #11055

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🦋 Changeset detected

Latest commit: af4cb5b

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

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[dummdidumm]

I added this code here instead of inside serialize_get_binding to not bloat that function even further and to not having to adjust the other callsites (AFAIK we only need that logic here)

[trueadm]

This is also a good opportunity to not allow props.$$events etc

[dummdidumm]

opened #12207 as a follow-up that does that; this PR should be merged first

[trueadm]

LGTM

[david-plugge]

I assume the props are not bindable and there is no way to change that, is that correct?

[dummdidumm]

Yes, you can only use this if you don't have fallback values or bindable props.