Preserve JSX tag syntax in autofmt

[nicoburns]

Summary

Stacked on #5730. Makes dx fmt/autofmt keep rsx written in the JSX/XML tag syntax in that style instead of rewriting it into block syntax.

• dioxus-rsx: Element and Component gain a tag_syntax: bool field, set by the JSX parser, so downstream consumers know which style the node was written in.
• dioxus-autofmt: write_element/write_component dispatch to a new write_jsx_tag when tag_syntax is set:
  • self-closing tags for empty children: <img src="image.png" />
  • single short child inlined: <h1>"Hello"</h1>
  • attributes inline in the opening tag when short, otherwise one per line with the closing > on its own line
  • attribute values printed as name="literal" / name={expr}, shorthand collapsing (disabled={disabled} → disabled), spreads as {..attrs}, dashed custom attributes unquoted (data-count="1"), and components printed without the turbofish (<Outlet<R>>)

Mixed block/JSX styles are preserved as written, since dispatch happens per node.

Tests: idempotency sample (tests/samples/jsx.rsx) and a normalization test (tests/wrong/jsx-4sp*).

Link to Devin session: https://dioxus.staging.devinenterprise.com/sessions/418cbef546c844b6b40c575b1ae28376
Requested by: @nicoburns

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