[Feature Request] Implement built-in `/create-*` skills similar to those in VS Code

[doggy8088]

Describe the feature or problem you'd like to solve

I'd like to create skill, agent, hook, prompt, ... easily in Copilot CLI

Proposed solution

Just like VS Code, it is very convenient.

Example prompts or workflows

Simply type /create-skill to easily create a skill.

Additional context