Allow extending auto-imports config

[harlan-zw]

Is your feature request related to a problem? Please describe.

As far as I'm aware, there's no way to extend the auto-import functions used by iles.

It would be useful for devs as they could auto-import from specific folders easily (e.g Nuxt auto-imports composables dir), as well as module authors who can register auto-imported functions.

Describe the solution you'd like

A config similar to components which can easily be extended

Describe alternatives you've considered

Don't mind the implementation

Additional context
Add any other context or screenshots about the feature request here.

[ElMassimo]

Hi Harlan! Thanks for the suggestion!

The auto-import logic in îles is very rudimentary. It works for the intended purposes, but it's not something that can be easily extended at the moment.

It might be worth replacing this with unplugin-auto-import internally, in which case we could expose configuration options, as is the case with unplugin-vue-components.