Notify Data Owners When Someone Subscribes or Requests Access to Their Datasets

[klondikemarlen]

OUT OF CURRENT SCOPE

Context

Is your feature request related to a problem? Please describe.
When a User subscribes to a dataset or requests access to a dataset, the data owner will not be aware of this until the log into in the app.

Describe the solution you'd like
Add simple mail action into the api/src/services/access-requests/create-service.ts to notify data owners that they have new users, or a pending request to approve.

Will require building templates for each of the two cases.