add action create --copy

[rabbah]

Is your feature request related to a problem? Please describe.
Sometimes, it is convenient to create an action by copying an other. The wsk cli supports wsk action create newAction --copy oldAction as an example.

Describe the solution you'd like
Allow action create with --copy as convenience to copying an existing action to a new name.

Describe alternatives you've considered
The alternative is to manually get the action, and save the code, params and annotations to files then recreate the action.

[purplecabbage]

aio runtime:action:create --copy ACTIONNAME [ACTIONPATH]