ShellApplicationRunner should have behaviour without arguments

[jvalkeal]

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Starting from 3.3.x NonInteractiveShellRunner is only active runner on default. While it was always possible to disable InteractiveShellRunner to get into this behaviour, NonInteractiveShellRunner doesn't really do anything if no arguments were given.

Traditionally just running app as is i.e. prints main help. Saying NonInteractiveShellRunner doesn't do anything is a bit wrong as it's not even chosen if there's no arguments. Should think where to handle this case and how?

Might be a role for ShellApplicationRunner to handle this.