feat: add Tailwind class name sorting (#552)

[todor-a]

Fixes #552. Adds opt-in Tailwind class sorting aligned with prettier-plugin-tailwindcss.

Problem

Tailwind users often rely on Prettier's Tailwind plugin to keep utility classes in a stable recommended order.

const value = <div className="p-4 flex bg-red-500 text-white" />;

Currently dprint-plugin-typescript preserves the input order, so projects that use dprint cannot opt into that Tailwind ordering for JSX class attributes or common class helper calls.

Fix

Add jsx.sortClassNames with a new tailwind value. The default remains maintain.

When enabled, the formatter sorts Tailwind class lists in:

• JSX class and className string attributes
• string literals, object keys, and simple template literals inside className={...} expression containers
• configured helper calls via jsx.sortClassNames.functions, for example cn, classnames, or tw
• configured tagged template literals via the same function list

The sorter follows the same broad behavior as prettier-plugin-tailwindcss for the covered cases: custom classes stay first, whitespace is collapsed, duplicate classes are removed, and variants sort after base utilities.

Behavior

input	config	after
<div className="p-4 flex" />	default	unchanged
<div className="p-4 flex" />	jsx.sortClassNames: tailwind	<div className="flex p-4" />
className={cn("p-4 flex")}	jsx.sortClassNames: tailwind	string inside expression sorted
cn("p-4 flex")	jsx.sortClassNames.functions: ["cn"]	cn("flex p-4")
tw`p-4 flex`	jsx.sortClassNames.functions: ["tw"]	tw`flex p-4`

Spec and docs updates

New JSX attribute specs cover:

• default no-op behavior
• Tailwind ordering for class and className
• public prettier-plugin-tailwindcss examples
• custom class ordering
• whitespace collapse and duplicate removal
• className={...} expression containers
• configured function calls and tagged templates

Docs updates cover:

• README configuration example
• generated schema descriptions for jsx.sortClassNames and jsx.sortClassNames.functions

Cross-referenced against prettier-plugin-tailwindcss docs/source and Oxc's Tailwind sorting tests.

cargo test passes.