Fixing authorization for datasets endpoint and updating casl

[nitrosx]

Description

Authorization is managed through the casl module. The datasets endpoint have been all updated to use properly casl, but casl does not play nicely with mongoose models.

Motivation

We want to use the casl module to manage authorization.

Fixes:

• Added test files for authorization

Changes:

• datasets modules

Tests included/Docs Updated?

• Included for each change/fix?
• Passing? (Merge will not be approved unless this is checked)
• Docs updated?
• New packages used/requires npm install?
• Toggle added for new features?