Shell Configuration

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

Allow to configure which shell-type Copilot should use (powershell/bash/..)

### Proposed solution

I'm running Copilot CLI on Windows in my bash, however copilot executes all his commands as powershell.
It would be great to tell/configure copilot to use the bash commands (ls/grep/curl ...) on windows as well

### Example prompts or workflows

_No response_

### Additional context

_No response_