Add OSC 9;9 support

[merrijo]

I'm currently running clink 0.4.9 with the new Windows Terminal and found that OSC 9;9 commands are being stripped out. From version 1.6+ this is used to create a duplicate pane/tab in the same directory. Are there plans to support OSC 9;9 in the future?

[chrisant996]

This repo has been abandoned for a few years. A fork has become the new de facto official repo: chrisant996/clink where Clink v1.2.7 is available.

Please open the issue there, and please explain when/how the OSC 9;9 escape code is being used, and when/where are they being stripped from.