Move the background item to the right

[leolost2605]

Includes #523 as that makes this a trivial change.

I wanted to try this and ended up liking it quite a bit better so proposing it here. A few arguments in favor of this:

• It follows the hig better which says the rarer something is used the more to the right it should be placed and I don't think people interact very often with the background item
• IMO this also helps with the feeling that they are to prominent which wasn't helped by them being right in the middle
• It brings more separation because there is always a whole icon with a + between the rest of the workspaces and the background apps

Fixes #447
Fixes #548