Add slash command '/tools' to list all tools available

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

Currently it is very hard to find out what the capabilites of copilot cli are in terms of what tools it can acces to help you

### Proposed solution

A slash command `/tools` or something similar that lists all tools available, comparable to like something [Gemini Cli](https://github.com/google-gemini/gemini-cli) has, would improve the discoverability of the current copilot capabilities a lot.

### Example prompts or workflows

User Input: `/tools`
Output:
```txt
- bash - Run bash commands in interactive sessions (sync/async/detached modes)
- view - View files and directories with line numbers
- create - Create new files with specified content
- edit - Make string replacements in existing files
- write_bash - Send input to running bash sessions
- read_bash - Read output from async bash commands
- stop_bash - Stop running bash sessions
```

### Additional context

_No response_