Add a loading indicator to empty tables

[dlmarion]

This change adds a single column with an empty header row and a loading indicator to the tables that are managed by the server_process_common.js file. The logic in the server_process_common.js file will remove the thead and tbody elements from the table before populating it with columns and rows.

[DomGarguilo]

Things seem to work well here and do the intended job:

The only things I can think of that are just preference are:

1. could refactor this spinner html block into its own file then replace the repeated code with something like <#include "table_loading.ftl">
2. The spinner and the "Loading..." text are far apart and might look better next to one another. Might be able to do that by replacing the ms-auto with gap-2 or something.

Putting this loading view into a "fake" table seems a bit hacky but seems to work well and looks fine so I don't think its an issue.