feat: aliases support

[jrmncos]

Hi team! Thanks for the great plugin!
I need the approval of this PR 🙏🏽

If a command with a topic has an alias the autocomplete doesn't show it

some-cli/
   src/
      commands/
         some-topic/
            my-awesome-command

class MyAwesomeCommand extends Command {
    static alias = ['my-awesome-command']
    ...
}

Previous behavior:
some-cli TAB TAB => some-topic

Actual behavior:
some-cli TAB TAB => some-topic and my-awesome-command

Thanks a lot!

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @jrmncos to sign the Salesforce.com Contributor License Agreement.

[RodEsp]

Overall looks good to me.

@RasPhilCo since this is pretty simple functionality would you happen to know why it wasn't added from the get-go? Maybe there's a good reason we don't want this that I'm overlooking?

[RodEsp]

Sync'ed with @RasPhilCo on this in Slack.

I don't think there should be a problem merging this.