Add custom remark2rehype handlers

[ShadiestGoat]

Fixes #260

As a note - this looks like it adds a new dep mdast-util-to-hast. However, this actually just moves it out of the dependency of another pkg.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: b9c626806b91fca2ab47ff3546a7a9c8d557f19e

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

This PR includes changesets to release 1 package

| Name | Type | | ----------------- | ----- | | svelte-exmarkdown | Minor |

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[ShadiestGoat]

@ssssota hmm.. is it up to me to add changesets in this PR? I can do it if needed

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 45.45455% with 18 lines in your changes missing coverage. Please review.

Project coverage is 92.14%. Comparing base (471ba46) to head (b9c6268).

Files with missing lines	Patch %	Lines
src/lib/utils.ts	45.45%	18 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #261 +/- ## ========================================== - Coverage 97.32% 92.14% -5.18% ========================================== Files 8 8 Lines 299 331 +32 Branches 46 30 -16 ========================================== + Hits 291 305 +14 - Misses 8 26 +18 ```

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[ssssota]

@ShadiestGoat Please run pnpm fmt to format code.

[ShadiestGoat]

Hey @ssssota sorry for the long wait, I ran the formatter