fix: ensure event precedence when spreading event attributes

[trueadm]

Turns out we aren't correctly handling spreading of attributes when there's a delegated event. This was a bit more involved than I'd like as we had to ensure delegated events occurred before the spread, but it makes sense.

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Name	Status	Preview	Comments	Updated (UTC)
svelte-5-preview	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 14, 2023 9:20pm

[dummdidumm]

I think we should fix this differently and add them to the spread array instead like we do when there's a mix of normal and spread attributes. While doing that we could then investigate how to Code-Golf event delegation inside the spread method.

[trueadm]

@dummdidumm Yeah, that's a good call. Would avoid the property lookup which is much nicer. Feel free to take over this PR. I think the bigger issue found is that snippets don't properly hydrate today because we don't serialize anchors in SSR (they look to be completely missing), plus I don't know why snippets are always blocks – they should only be if the snippet is dynamic, just like components work.

[dummdidumm]

• added event delegation to spread_attributes
• add event attributes to the spread when there is one
• fixed an edge case bug with event hoistability: if you did

<button on:click={increment}>
	clicks: {count}
</button>
<button on:click={increment} on:click={increment}>
	clicks: {count}
</button>

Then the first one would incorrectly determine that increment can be hoisted

• simplified the test to test only what's important to us here. The hydration thing should be handled separately