feat: Adds support for providing default URL parameters via the frontend

[owenconti]

This should resolve #49

This PR adds support for providing default URL values during runtime via the frontend. This works by providing methods within the wayfinder.ts that user-land code can call to set (or add individual) default parameters. These parameters are stored in a global Wayfinder window object.

When generating the URL for a controller, we merge in any set default parameters, making sure that we don't override any keys already set during the calling of the url method.

Note: in theory we don't need to use a window object here, but when running the test suite, it seems like I was getting different instances of the wayfinder.ts file, the default parameters that were set were getting lost.

Usage

Here's how I have it set up in our app. The benefit here is it is up to the user to decide where and when to apply the defaults:

  setup({ el, App, props }) {
    const root = createRoot(el);

    setDefaultParameters({
      workspace: props.initialPage.props.workspace.slug
    });

    root.render(<App {...props} />);
  },

---

One thing I have not figured out with this approach is non-optional parameters that do not have a default set via the URL facade on the backend. Wayfinder doesn't know that domain parameter is being set as a default and will be applied/set during the url() call:

[bdweix]

Nice work @owenconti - excited for this one!