Allow to pause copilot work

### Describe the feature or problem you'd like to solve

Sometimes thing go in wrong direction but there is no way to pause and give additional inf/instructions in such case.

### Proposed solution

Currently I can steer copilot during a session by entering some text and submit.

This works, but has some short comings:

1. if copilot wants to ask permissions the prompt window goes away while typing
2. Copilot is working and maybe doing other stuff and its hard to keep up as new text arrives in the meanwhile
3. If it is some lengthy task one is out of luck - example I need to fix an external build issue or install a certain tool version (java, maven, npm package, ...)

The other option is to completely cancel the operation what is also not good as then copilot has to keep up with what was previously done.

Instead, it would be good if copilot session could be paused (e.g. typing `/pause`) and it then waits, then I can install things, add directories or prepare a response and send it and then type `/resume` to let it continue.

### Example prompts or workflows

_No response_

### Additional context

_No response_