Allow to choose collection to put the forked notebook

[oluckyman]

I have different collections of notebooks for different projects. When I fork a notebook from a collection I want it to stay in the same collection. So I have to remember to add it into this collection manually.

Describe the solution you'd like Now there is a modal asking where to put the forked notebook

Would be nice to have the collections selector here with current collection selected.

[Martien]

+1