Add "Children" and "Media" tab to the Collection Content Type

[bseeger]

Add these tabs to list of tabs one will see on a Collection Object page when one is logged into the system.

This is currently accomplished via a View in the system for the Repository Item. Extend this to include Collection Objects to.

[bseeger]

I think this involves editing the existing views, but I didn't have any luck making that work - but maybe there was some caching thing there.

[bseeger]

It's more complicated then I thought involved some code changes. Including this info for whomever works on it:

• Members and Media tabs appear on non-Repository Item pages Islandora/documentation#1057
• https://github.com/Islandora/islandora/blob/8.x-1.x/src/EventSubscriber/AdminViewsRouteSubscriber.php

[bseeger]

Turns out it was because the Collection content didn't have the "field_model" field. Once I added that the tabs show up and work as expected.

[bseeger]

Solved by: #104

[bseeger]

Fixed by: #104