Add Filament guidelines

[ashleyhindle]

• Linear: https://linear.app/laravel/issue/AI-74/add-filament-guidelines

What & Why

This adds Filament core guidelines, and v4 guidelines. I paired with Dan Harrin on some of these, and there wasn't anything material we could add to v3 guidelines, so I've left them even though it feels wrong.

Filament's backwards compatibility & such is just so good that the core guidelines cover v3 too so far!

Working on these also highlighted an improvement we could make to calling artisan commands with interactive elements.

How I tested

1. Built a Filament blog with an admin panel with Filament v3
2. Built a Twitter clone with 'admin' panel with Filament v4

Notes/thoughts

• Seems to work really well atm. I don't want to go too far here, as the community will know better as they test it in full projects 👌