UI and routes for updating permissions for a collection of items

[ml-evs]

Following (the hopefully imminent) #830, we also need a sensible way for updating permissions on collections of items (raised by @PeterKraus in concat-lab/datalab-deployment#5).

We can easily add the new component to a collection, and somehow this should add the creators selected to all items within the collection. This should then be extended such that any future item that gets added to that collection also gets the same permissions (handy when e.g., the same group of people are working on the same set of items in a given project).

I think we will need to be quite delicate with our current permissions model, so I might do the simple implementation of this feature but add it behind a feature flag so that @PeterKraus can give feedback from his group.

There is also an outstanding bug with collections where an admin can add an item into a collection that they do not have permissions over; the original owner of the sample then does not have permissions to edit that sample, since they end up trying to reset the collection data that they do not know about (see #842)! This is probably also quite an urgent fix before working on this feature, as well as a few other related issues #790