ConEmu OSC progressbar support

[jerch]

Windows Terminal and VTE added support for a ConEmu specific OSC sequence to display process information on the taskbar button. This led the systemd folks to add it also into systemd command output for long running tasks.

We might want to offer an interface to also handle information from these ConEmu specific sequences, so integrators can work/implement their way to present that information to users. Imho this is not worth to be added to core, but maybe as an addon (maybe even considering several of the other ConEmu subsequences).

References:

• https://conemu.github.io/en/AnsiEscapeCodes.html#ConEmu_specific_OSC
• Implement ConEmu's OSC 9;4 to set the taskbar progress indicator microsoft/terminal#8055
• https://mastodon.social/@pid_eins/113406672373007116
• https://gitlab.gnome.org/GNOME/vte/-/issues/2845