[Console] [Event] Added COMMAND_ADD event

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | tba

This PR adds a COMMAND_ADD event. The primary use case is to enable listeners to modify the commands input definition, which is really useful in big CLI applications where commands share command traits.