Add Taskbar Progress Indicator on Windows

[89netraM]

ConEmu and Windows Terminal supports a OSC sequence for manipulating the Taskbar Progress Indicator. This can be used to display "spinners" even when the terminal (or tab) isn't active.

Following the documentation from ConEmu, this could be used by sending the sequence for indeterminate progress ESC ] 9 ; 4 ; 3 ; 0 ST when starting a spinner, and the sequence for removing progress ESC ] 9 ; 4 ; 0 ; 0 ST when stopping a spinner.

If this is something this project would benefit from, I would be happy to try my hand at implementing it.