Add Scenario and ScenarioFile models and views

[willemarcel]

Contributes to https://github.com/developmentseed/moz-proenergia-internal/issues/23 and https://github.com/developmentseed/moz-proenergia-internal/issues/24

I was unsure on how to deal with the model results data, and finally, I decided to implement a solution similar to what we did to the Vector datasets.

• User creates a Scenario
  • Chooses a Vector dataset that will be the geospatial component
  • Define the filter and popup fields
• User uploads a file that will be assigned to the Scenario

In a future PR, we will implement:

• Merge the model data from the uploaded file with the vector dataset in a PMTiles
• Create a database table to store the model results data (only the columns set in the popup_fields, as we will only need to return that data in the API).

[LanesGood]

Discussed in standup: it makes sense to respect the terms and relationships of the concepts of "model" (PUE, LCOE, etc) and "scenario" established in the existing data. We will include a "model" in the database model and endpoints, and each model may then have multiple "scenarios." The filters and popups are then defined on the model, and do not need to be redefined or copied for each scenario.