fix: support shorthand attribute syntax on enhanced-img

[LorisSigrist]

This PR adds support for the Attribute shorthand syntax on <enhanced:img components.
It is now possible to write the following code:

<script>
  import src from "$lib/myImage.png?enhanced"
</script>

<enhanced:img {src} />

Previously this would error

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🦋 Changeset detected

Latest commit: e648afe

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/enhanced-img	Patch

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[benmccann]

I just pushed a small change to change this from "opt-in test" to "attribute shorthand test"

[benmccann]

Thank you so much for this! Sorry it took me awhile to get to reviewing it. I'll merge it in just a minute when the CI turns green