feat: allow file input in applyTransform test util

[paul-vd]

Fixes: #150

This allows to define the path for the file in the transformer, for example

    const result = await applyTransform(
      transformer,
      {
        path: "src/components/Example.tsx",
        source: `
        import React, { useState } from "react";
      
        export default function Example() {
        const [state] = useState("Hello World");
      
        return <div>{state}</div>;
      }`,
      },
      { parser: "tsx" }
    );

[danieldelcore]

Looks good to me! Thanks for contributing!

[danieldelcore]

Oh btw, could you please generate a changeset for the package so it can be automatically versioned and deployed 🙏

yarn changeset and follow the prompts 👍

[paul-vd]

@danieldelcore I ran the changeset, can you please confirm if it is correct?

[danieldelcore]

Loooks good!! Thanks again!