New icon for PowerShell Core (PowerShell#4848)

* added new icon

* added new icon

* update icon to new version of console image with avatar colors

* added svg for blue Windows PowerShell icon

* changed default to the black icon

* added custom bitmaps to the installer

* fixed `launch powershell` checkbox so it shows up more nicely as the default checkbox
has a grey background

also reformatted the xml using a xml formatter to make it easier to read

* address PR feedback

Author: SteveL-MSFT