perf: babel-plugin exports static methods type

[nonzzz]

Make @stylexjs/babel-plugin types happy.The pr exports method styleXTransform static methods types.

[nmn]

Suggested change

	export type StyleXTransformObj = {
	(): PluginObj<>,
	withOptions: typeof styleXTransform.withOptions,
	processStylexRules: typeof processStylexRules,
	...
	};
	export type StyleXTransformObj = $ReadOnly<{
	(): PluginObj<>,
	withOptions: typeof styleXTransform.withOptions,
	processStylexRules: typeof processStylexRules,
	...
	}>;

[nmn]

Would prefer the type to be read-only if possible.

[nmn]

This is a nice improvement. Thanks!