Support progress reporting

[Jan200101]

Some linux applications (namely flatpak and selinux with pull-requests existing for other cargo and possibly other applications) have started to implement progress reporting via the ConEmu OSC 9;4 command

In essence this would allow a program to convey its progress in a way that wouldn't need the terminal active

How to exactly implement progress reports is up to debate, some options are:

• include progress in tab and or window title
• set progress on the taskbar

What other terminals do:

• alacritty: doesn't support it, no explanation why

• kitty & foot: check for OSC 9;4 specifically and drop it entirely

• windows terminal: shows progress as a circle in the tab (added by this PR)
  

• conemu (where this originated): shows a progress number in the tab title
  

• Gnome VTE library (Gnome Terminal, guake, etc.): implemented

• ptyxis: shows progress as a circle in the tab