Create get all integrations api route

We need an api route to get all integrations. This will power the integrations ui page and unblock #9.

The seed script does not currently create any integrations so we will need to add that for testing.
We also need to create models for integrations objects.

Start by locating the API route entry point, the seed script, and the existing model definitions. Check how integrations are represented for the integrations UI page and how seeded data is loaded. Done means the models exist, the seed script creates integrations for testing, and an API route returns all integrations.

Escrito por el modelo de indexación a partir del texto del issue.