* Allow the AppIconBanner tool to be called with purely the build number.
And use that for the Element Pro Nightly.
* Use a build setting to determine Nightly builds.
We've haven't really been using these and they're proving to be quite a chore to keep running.
Also, we recently needed an external demo build and we chose to go with custom build on top of testflight instead.
As such it's been decided that we can go ahead and remove them.