Run local extenders before booting service providers
Run local extenders before booting service providers

We still need to discuss the priority of local extenders vs. those
from enabled extensions, but let's first fix the actual bug.

Refs #1708.

flarum/core,flarum/core,datitisev/core,datitisev/core,datitisev/core,datitisev/core,flarum/core