Taxonomy subscriptions

[pedro-gutierrez]

Is your feature request related to a problem? Please describe.

At the moment we don't have a real time feed of aid taxonomy updates.

As a group member
I want to be notified when a new category, mods or item are created or modified.
So that so that I keep track of the latest Aid Taxonomy updates

Describe the solution you'd like
New GraphQL subscriptions for category, mods and item

Describe alternatives you've considered
Using GraphQL subscriptions:

• Add new tests (investigate the best pattern for testing GraphQL subscriptions)
• Add the new subscriptions to the GraphQL schema
• Setup the Phoenix endpoint so that the GraphQL subscriptions are bound to a Phoenix socket