feat: provide your own mapbox library/geocoder

[Duckapple]

In scenarios where you deploy your own web app, with sveltekit or not, using the window object is fine, since you control everything about the page.

However, in browser extensions, we can't expect to populate the window object, since we might collide with the underlying page or other extensions. If the versions are mismatched, and you depend on something older or newer than the others, your extension and the page might break in unexpected ways!

This PR allows you to Bring Your Own Mapbox, by providing the library directly to the component. By providing the library yourself, you completely avoid using the window object, which in turn lets the underlying page do whatever it wants without being bothered by your extension.

[Duckapple]

An alternative API would be to put the mapbox library in a context, where the setContext could be exposed as API for the consumer of this package. That way, the user still has very granular control, without having to prop-drill or import the library whenever they use a map.