Make "aaz run -c" switch non-required

[jeremyhouser-ms]

The -c switch is used to specify the command_modules in azure-cli

when working with code which is not present in azure-cli, this switch is unnecessary. Requiring it creates a dependency to either give it a dummy directory to find the path it expects, download azure-cli and use it, or give it a dummy directory without the path it expects, which generates an error that doesn't matter to us.

Instead, I would like to see a message in the help for -c and -s/--sm that states when you should use the given switch.

Please let me know what you think, thank you.