Add SSO for admin users

[Kamil-Herbetko]

We need to create endpoint for loging in with SSO. So we need to create 3 things:

• User model
• Endpoints for authentication
• Schemas that will define inputs accepted within defined endpoint methods

Authenticated user should get a token that will be validated at certain protected endpoints. For more information check SSO with fastAPI tutorial and fastAPI documentation

[Kamil-Herbetko]

There was no need for user model (As Mr. Jóźwiak requrested), thus, only JWT with SSO