Improve MyList UI to address slow object load times in request modals

[HaSistrunk]

Is your feature request related to a problem? Please describe.

Based on reports/requests for support from multiple researchers in Reading Room, it is not always clear to users when objects are loading and need to finish loading in the request modal before they can be selected. Users will try to select checkbox inputs while loading is underway, be unable to select, and think that there is an error.

My testing showed load times to be ~1 min (30 items) to 1 min 45 sec (100 items).

During multiple tests, I got an error after ~> 1.5 min of loading with between 50-100 objects in my list: The request to https://request-broker.rockarch.org/api/process-request/parse-batch failed. Error message: Network error. However, I could not reproduce this consistently so it may have been my personal network connection.

Describe the solution you'd like

Update the modal UI to show a "Loading..." message (like when the collection content is loading) instead of the skeletons that currently display for any restrictions associated with the object. This solution should be a clearer communication to the user about what is happening.

Describe alternatives you've considered

1+ minutes to load is a long time. Consider redesigning the My List UI overall so that users select which items they will request before opening the request form so that only those objects will load instead of all objects.