feat: add self-closing-tags migration

[dummdidumm]

Companion to sveltejs/svelte#11114. This adds an npx svelte-migrate self-closing-tags migration that replaces all the self-closing non-void elements in your .svelte files.

Alternative to #12102 with the following adjustments:

• doesn't migrate slots that are not real custom element slots (will make diff much less noisy)
• doesn't migrate when namespace is foreign
• leaves tag-like strings inside scripts/styles etc alone

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🦋 Changeset detected

Latest commit: 4a5b9ec181008d0bbba1562c7f072f7a1a47a88b

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

This PR includes changesets to release 1 package

| Name | Type | | -------------- | ----- | | svelte-migrate | Minor |

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