[1.x] Ensure models directory exists

[rojtjo]

I noticed while attempting to install Jetstream in an existing project that it crashed halfway through because I didn't have a models directory.
This change ensures the directory exists.

[taylorotwell]

All new 8.x projects already have a models directory.

[rojtjo]

True, the problem only arises when upgrading from an older version, or when you decide to install Jetstream later after already having moved the User model to a different directory (and obviously removing the Models/ directory).

[driesvints]

@rojtjo Jetstream is meant for new Laravel installs. If you're migrating your existing app to Jetstream you'll need to do some manual work.

[rojtjo]

Yeah, I figured already! Just assumed (when installing the first time) that it was checking if a models directory exists like it does for the make:model command. 😅

Anyways, thanks for the explanation!