Objectchooser filter try4

Thanks for reviewing the previous ones @godiard.
I think this fixes your comments :smile:.

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On the old version the users are given a button clear search
if they don't have objects of the type the activity wanted. This
is confusing as it implies that users can insert whatever they
want as an image for example.

This fix hides the button when the user does not have any of the
requested object type. It also makes the button go back to the
activities original filter

There is probably a ticket about this, but I don't know where it is.