Preserve JSX tag syntax in autofmt

[nicoburns]

Summary

Top of the stack #5883 → #5730 → this. Makes dx fmt/autofmt keep rsx written in the JSX/XML tag syntax in that syntax instead of rewriting it into block syntax.

write_element/write_component dispatch to a new write_tag when the node's NodeDelimiter (from #5730) is a tag. Mixed block/tag styles are preserved as written, since dispatch happens per node. Incomplete tags (which only parse with diagnostics) are not formatted.

Layout:

• self-closing tags for empty bodies: <img src="image.png" />
• a single short child is inlined: <h1>"Hello"</h1>
• attributes stay in the open tag when short, otherwise one per line with the closing > / /> on its own line; multiline values (closures, long if chains) are indented relative to their attribute
• attribute values are printed as name="literal" / name={expr}, shorthand collapses (disabled={disabled} → disabled), spreads as {..attrs}, dashed custom attributes unquoted (data-count="1"), and components without the turbofish (<Outlet<R>>)

Comments and blank lines are located from the tag tokens and kept, using the comment helpers from #5883 (write_comment_only_body, write_closing_line, has_leading_comments, inline_comment):

// Before a tag
<div
    // Before an attribute
    class="a"
    id={user_id} // After an attribute
    {..attrs} // After a spread
>
    <h1>"Hello"</h1> // After a tag

    <p> // After an open tag
        "text"
    </p>
    // Before the closing tag
</div>
<section>
    // Only a comment
</section>

Attributes that have comments are always put on their own lines, so the output is the same on every pass.

Comments in the middle of an open tag are kept too (second commit), mirroring what #5883 does for the block syntax. A comment after the tag name stays there, and one between = and a value stays above the value:

<div // After the name
    class= // After the equals sign
        "a"
    id=
        // Above the value
        {id}
>

Comments inside an if attribute value and inside for / if headers go through the code from #5883.

Tests: idempotency samples (tests/samples/jsx.rsx, tests/samples/jsx_comments.rsx) and normalization tests (tests/wrong/jsx-4sp*, tests/wrong/jsx-comments*).

Link to Devin session: https://dioxus.staging.devinenterprise.com/sessions/99eedb36d44345dc8ce0f3ed5c460bd6
Open in Devin Desktop: https://dioxus.staging.devinenterprise.com/desktop/session/99eedb36d44345dc8ce0f3ed5c460bd6?variant=devin-insiders
Requested by: @nicoburns

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