More robust/flexible loading component

[jonasKjellerup]

The current loading (fstjerne spinner) component is somewhat of an adhoc solution.

It would be nice to have a version that:

• Allows more than one spinner to exist on the page.
• Has a mode that allows a status text to be included.
• Is able to switch between not-interacting with page flow and doing so.
  • This would allow for a default spinner to be present in the base layout such that individual modules that need to support a loading screen would not have to add it. (Its default state should be able to be set from the pug file that inherits the base layout)