Feature request: make copy-frameworks optionally not strip architectures

In any project with several Carthage dependencies, calling `/usr/local/bin/carthage copy-frameworks` starts becoming a very large part of the compilation time. AFAIK most of that time is due to stripping architectures.

However, I just realized that if we made that optional, we could make it only do that when archiving for submission, and in that way make iteration times much lower.

Start at the `carthage copy-frameworks` command and trace where architectures are stripped. Check the existing command tests and determine how an option can disable stripping without changing current default behavior. Done means iterative copying can skip stripping while archive workflows can still perform it.

Written by the indexing model from the issue text.