Use calculated height, as opposed to hardcoded height, for window

sb-admin uses hardcoded values, so at smaller heights, there's excess
whitespace.

Using 100vh uses the 'viewport height' as the base, which dynamically changes
with rescaling. Removing the 52px ensures that the header height is removed
from the calculation.

Result: any resizing has the no scrollbar until the height is sufficently short
to not be able to show all elements on the page.
Add select-all button to add all select2 search results

Based on https://github.com/tamble/select2/compare/ftr-594
Button names changed to reflect functionality w/ajax-ness

Note: only listed search results, not those hidden behind 'loading..' will be
added. That is, all current objects. However, if you're trying to add more than
64 graphs at once, you're asking for trouble. It might work, but you'll
probably crash your browser