This replaces the cumbersome system we had for giving users feedback
on settings state changes in the display settings UI.
We expect this new system to be what we will attempt to migrate other
settings widgets to match over the coming weeks and months. It also
provides the opportunity to significant refactor away a lot of the
code duplication in settings_display.js.
Thanks to Brock Whittaker for redoing the styling and improving the
code simplicity.
Fixes#7622.
In this we fix the positioning of the loading spinner on the home page
when its loaded for the first time. First time here does not mean first
time use but means first time of a new session.