Correctly check existence of target directory in `copy_recursive` function (#6875)

Fixes https://github.com/zed-industries/zed/issues/6778

Release Notes:

- Fixed issue where copy-paste for folders was not working in the
project panel
([#6778](https://github.com/zed-industries/zed/issues/6778)).
49542757fdGeorge Munyoro committed on 1/29/2024, 10:06:02 AM· committed by GitHubparent9ef830e
2 files changedLine totals unavailable