[FEATURE] use mcdev build for copy

[JoernBerkefeld]

We could add a reserved market name "CLONE" that tells build to ignore existing markets and act as a copy/ clone tool.

Prerequisite for this is that build no longer by default writes into the template folder. There is a ticket upcoming in 7.5 that will allow that

Why?
This would eliminate the otherwise duplicate logic of finding relevant files to copy