Bug 31795: Add REST endpoint to add an authority

Bug 31795: Add REST endpoint to add an authority

To test:
1. Apply patch
2. Set RESTBasicAuth preference to true
3. Make a POST request to /api/v1/authorities with one of the following content type header
  - application/json
  - application/marcxml+xml
  - application/marc-in-json
  - application/marc
4. If content type is other than application/json, then add the following header to the request: "x-authority-type: <auth type code>"
5. Check that the authority is created
6. Sign off

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>