promp file path can be passed by parameter

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

_No response_

### Proposed solution

Currently, you are allow to do ```copilot -p "prompt"```
If prompts are large, or contain quotes or other special characters, it would be better to have the prompt in a file and pass it to the cli (ex ```copilot -f /prompt.md```) instead of having to use cat or other commands.

### Example prompts or workflows

_No response_

### Additional context

_No response_