Terminal tab progress reporting using OSC 9;4; ANSI sequence

[bluetech]

What's the problem this feature will solve?

I've learned about a new feature that some terminal emulators are starting to add, which shows progress of a process on the terminal tab. I've learned about it from here. Screenshot of how it will look in Gnome (Linux) from here. Seems like a good fit for pytest, allowing a user start a pytest run, do something in another tab and see at a glance the pytest progress.

Describe the solution you'd like

The sequence is documented here.

It should be implemented in the terminal plugin, in TerminalReporter, probably in pytest_runtest_logreport.

My only concern is that it's a global effect on the terminal tab, which pytest doesn't have until now as far as I remember. But it's probably fine and if someone complains we can make it optional.