Add ability to disable OSC 9 progress bar in tab and taskbar

### Description of the new feature

I find the progress bar showing up in various tools (like when Rust is compiling) to be very distracting.

Furthermore often it gets stuck, perhaps this is related to the keyboard cursor blinking rate being disabled -- as there are similar Windows bugs related to that specific feature.

Still, it doesn't seem like we can disable this taskbar progress bar on Windows. So it would be nice if we could disable it in the Terminal.

### Proposed technical implementation details

_No response_

Start at the OSC 9 progress handling entry point and trace how its state reaches the tab and Windows taskbar displays. Determine the user-facing disable behavior, then verify that disabling it suppresses both progress bars while leaving other terminal progress behavior intact, including the stuck-progress scenario described in the issue.

Written by the indexing model from the issue text.