Show load indicator and disallow selection until left side content is fully loaded

[fedorov]

Currently, initial list is loaded sorted by Alpha, and there is no indication to the user that the page is not fully loaded. After several seconds, when the page is loaded, the list is sorted by count, and the list is completely changed.

The problem with the current behavior is that while the page is not fully loaded, the checkboxes can still be checked. Even more confusing, the actual checkbox label will change between the time user checked and selection is applied!

[fedorov]

As discussed with @s-paquette, we cannot change the default behavior to load it ordered by count because on initial load we do not have the counts, so the only way to solve this is to add the spinner to block the UI.