[8.x] Factory autocompletion

[macbookandrew]

This is entirely the work of @lepikhinb as posted in https://forum.archte.ch/laravel/t/factory-autocompletion

He gave permission here for me to submit this PR.

Add autocompletion to your Laravel factories.

I've created a simple stub that adds some extra docblocks to newly created factories. Publish it to the stubs directory, and the next time you generate a factory, it will contain them.

[taylorotwell]

These stubs are customizable so you can publish them add whatever you want to your default stubs.

[macbookandrew]

I know, but thought it might be helpful to the community in general.

Thanks anyway!