Moving the Cli input into new class

Why?
I'm working on a console app, which uses commands as separate classes, very similar to these in [framework-status](https://github.com/mbabker/framework-status/tree/master/cli/Command) repository.

I'd like commands to have a possibility to be executed outside the `AbstractCliApplication`, anyway in my opinion commands don't not necessarily need access to whole application object. Usually it's just output, input and some objects from container.

At this moment the CLI application [input is a method](https://github.com/joomla-framework/application/blob/master/src/AbstractCliApplication.php#L103), moving into new class allows to pass it along or use own one with predefined batch of inputs.

Maybe even good for testing, but I'm not there yet.