More attention-grabbing inline loaders

Previously, when you pushed a branch you'd get a fairly loud (i.e. attention grabbing) popup so it was clear what was happening. We switched from that to a non-popup inline loader against the branch because it was often annoying to cancel out of the popup to do something else while the push continued in the background.

But, the new loader is not very attention grabbing and that can be startling for users used to the popup (which would be pretty much everybody currently using lazygit).

I want to experiment with making the inline loader louder. For example:
* make it bold (if it's not already)
* make the loader take up more space (even though I really am a fan of a single character spinner)
* highlight the branch name while the loader is aside it
* turn the screen's border to blue just to say that _something_ is happening

These are all just random ideas. It would be good to experiment and see what works well.

I'm using branches as an example above but this applies to all inline statuses (e.g. tags)