Fix copy-pasting pixel data from animated layers

Now when you copy-paste animated frame data, it is pasted into
exactly the same time range position. It means that if you later
merge down this data back to the original layer, you will not get
a data loss. The data will be merged exactly into the position where
it has been taken from.

BUG:364162
CC:kimageshop@kde.org
(cherry picked from commit 39ec1d47a59425969814dc840209ec2433bdd133)