Support diagram profile activity store/restore in model export/import

Support diagram profile activity store/restore in model export/import

Diagram profile selections are stored in the "profiles" workspace
persistent virtual graph. They cannot be done in the persistent database
because we do not want the profile selections to be part of the database
version/undo history. This just doesn't fit the current way of using
diagram profiles.

The code introduced in this commit needs to be put to use in
product-specific custom export/import logic and copy/paste handlers to
take advantage of it.

refs #7854

Change-Id: Ib996144f1afa376a1563e4309fe41421ee4da529
(cherry picked from commit 95e05b3cc3208ec57118e8167a090c9b90edfaf2)