Rails admin upgrade from v2 to v3

This clears up the jquery-ui vulnerability since RailsAdmin 3 does not use jquery-ui. The Rails vulnerability is also fixed in here.

A couple things to note:

I also removed a lot of unused capistrano stuff we don't need now that we use Argo and stuff to deploy
We were using a gem called rails_admin_toggleable to allow admins to toggle some booleans from the list views. I don't think this was really being used. Regardless, it had to be removed because it is not maintained and not compatible with RailsAdmin 3.
RailsAdmin 3 has CSS that needs bundling, so css-bundling was added. It works similarly to js-bundling.
We have a lot of custom actions and views that are basically copy-pasted from the RailsAdmin source code and slightly modified for our needs. I had to go through and update the code in those to match the RailsAdmin 3 syntax.
Another ancillary thing in this PR is: I fixed the Activity Insight Publication Exporter. I figured I'd fix that since I had to update some of the code for that action.
Zeitwerk/autoloading did not like this upgrade. The only way I could get this to work was by wrapping the RailsAdmin configuration initialization in a to_prepare block. I have a comment about that in the initializer.

psu-libraries / researcher-metadata