Feature Request: Add /list-tools command to view currently allowed tools

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

Apparently there's no command to list currently allowed tools.

### Proposed solution

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

Currently, there is no way to view which tools have been approved for use during a Copilot CLI session. Users can see allowed directories with `/list-dirs` and reset tool permissions with `/reset-allowed-tools`, but there's no equivalent command to list currently allowed tools.

This makes it difficult to:
- Audit what permissions have been granted during a session
- Understand which tools are currently approved.
- Make informed decisions about whether to use `/reset-allowed-tools`

### Proposed solution

Add a `/list-tools` slash command that displays:
- All tools currently allowed for this session
- Whether each tool was approved once or for the entire session
- When each tool was approved

Example output:

Allowed tools:
1. chmod (session-wide, approved at 11:15:32)
2. node (session-wide, approved at 11:16:45)
3. touch (once) - approved at 11:20:12)

### Additional context

This would mirror the existing `/list-dirs` functionality and provide better transparency for the permission system, helping users maintain security awareness while working with Copilot CLI.

### Example prompts or workflows

```bash
Allowed tools:
1. chmod (session-wide, approved at 11:15:32)
2. node (session-wide, approved at 11:16:45)
3. touch (once) - approved at 11:20:12)
```

/list-tools

### Additional context

_No response_