Use shared_examples for testing publication types controllers

[Janell-Huyck]

We have a lot of duplicated code and testing going on for the controllers of each of our publication types. For this issue, we should:

1. Create a detailed set of tests for PublicationsController, testing each of the CRUD functions it offers, and including testing for:

• template rendering
• error handling
• redirection logic
• flash messages
• authentication and authorization.

2. Create a shared example for CRUD operations that checks only the happy path for each of the functions.
3. Apply this shared example to one of the publication types, removing the CRUD testing from within the controller spec. Have this example reviewed as a PR.
4. Apply the shared example to all other publication types, using 1 PR per publication type.

[Janell-Huyck]

https://ucdts.atlassian.net/browse/LIBAAEC-14