Popup Load Optimizations

[quoid]

Optimize the loading experience for the popup:

• do the updates check some time after the popup loads
• figure out a better way for checking/updating @requireed assets that is outside the popupInit function

[quoid]

related #276

[quoid]

Another note:

If the goal is to track userscript updates and to not check every single time the popup opens, whether or not there are userscript updates should be stored in local storage so that the update notification (red dot) is visible until the updates are applied. This assumes the "red dot" indicator remains.

Currently, when the "red dot" indicator shows, it only when update check happens. If the user decided to not update the userscripts, the next time the popup loads, there is no indicator, even though those updates are still not applied to the userscript(s).

Another consideration is that a user could update the userscript(s) outside of the the popup. It could happen manually or through the editor (on desktop).