Show selected auxiliary action
Support post modules

I kinda hate this code.

TODO: Get rid of and/or and the extra parens.
Make the code more maintainable

Despite the code around it.

Thanks for the advice, @jlee-r7!
Break away the elsif into a separate if

In case exploits support actions for some crazy reason in the future.
Rename dump_auxiliary_action{,s}

To dump_module_action{,s} to accommodate post modules, etc.
Update print_error to include post modules
Fix tab completion for post actions
Rewrite existing code to use HasActions

And fix a bug in the initial use case where mod.action was dropped.
Update print_error to reflect new usage
Land #3962 - Show selected action