Provide reports and tools to view application instances

Currently Report gives no visibility over application instances. This makes it hard to use to help you work anything out and forces people to poke about in the limited admin pages. We should work out what reports and tools might help a user work out whether application instances are hooked up in the correct way in LMS.

## What do we need?

* At a minimum to be able to see the application instances for an organization (in report)
* Do we? Is LMS admin pages fine?
* We likely need an application instance "overview" to provide a jumping off point to search for them to go the other way too

We probably don't want to build anything amazingly complex in the report system. For example, if we are doing any fancy comparisons to try and suggest matching application instances or something, then doing it in LMS might be better.

## Tasks

* The above is a bit report centric. This could be an entirely LMS feature?
* Feedback from support:
* https://github.com/hypothesis/lms/issues/4965
* https://github.com/hypothesis/lms/issues/5001
* https://github.com/hypothesis/lms/issues/5002