Copy&Paste of flux container with children incompatible with EXT:content_defender

[z-gingco]

First of all, thanks for developing and supporting this great extension!
We are having an issue when using flux together with content_defender. Since flux 9.4.0 the functionality of copy-pasting containers with children elements has been broken for us, because content_defender assumes the elements are being pasted directly into the page column (in our case colPos 0) and not into the parent container and allows to paste only the parent container. After some investigation we found that reverting this commit 42d16f0 makes everything work again. Would it be possible for you to look into this? Thanks

[supercaccia]

Possible related #1895