Consider failing by default when copy_to_directory encounters conflicting files

[kormide]

Silently ignoring conflicts and not overwriting could be a source of tricky to find bugs. Both ignore and overwrite behaviours should be explicitly declared.

fyi @devversion

[gregmagolan]

Suppose we turn allow_overwrites into a conflict_strategy attribute with enum options overwrite, ignore and fail defaulting to fail.

[kormide]

Yeah I was thinking something along those lines as well.

[kormide]

Only downside is that there isn't an easy way to do this check with cp. We have to add some more complicated logic to search for potential conflicts first (I think).

[gregmagolan]

New impl will fail if there are conflicts and allow_overwrites is False on all platforms. Closing this. If we want to switch to a conflict_strategy attribute in the future then lets open up a new FR