Improved Seeding

[Brend-Smits]

Is your feature request related to a problem? Please describe.
Currently the seeding is done in the migrations, it should be moved out of the migrations. The migrations are unreadable at this point and hard to manage.

Describe the solution you'd like
The following things should be seeded in development only:

• Projects
• Users
• Highlighted Projects
• Embeds
• Collaborators

The following should be seeded in production only:

• Roles
• Single user

I personally recommend doing the seeding in the API project, like it was done in this commit
This way you can easily control what seeding is done in production and what seeding is done in development.

Additional context
This should also fix an issue where the collaborator ID is not unique and causes issues during build time.