Add ability to call commands programatically.

[lonnieezell]

• Refactored CommandRunner to bring all logic out to its own class.
• added new command common helper function to allow calling other commands programatically.
• Updated CLI class to be able to handle being ran when NOT on the cli. Will echo out the content instead.

[MGatner]

Looks great! I don't really have any projects right now where this would be applicable, but I'm tackling cron with Tasks soon and this will likely be a boon. I tested my most CLI-intensive module against it and all tests passed.

[lonnieezell]

@MGatner thanks for the review! Will definitely come in handy for cron stuff, I believe, which is part of why I built it. Also - was trying to write tests for a cache:clear command, and realized what a giant pain it was since the command runner was a controller. :)

[lonnieezell]

Oh - and don't forget the already started codeigniter4-tasks if you're going to be working on Tasks. :)

[MGatner]

Oh believe me I haven’t forgotten! I’m just holding off as long as I can before unleashing on it 😊