Add a facility to AccountModel for managing associations of public share
room passwords with the current account.  This will be used to retain share
room passwords over the extent of a login session.  (It could be extended
to retain passwords across logins and application sessions, using settings,
but that is not currently being implemented.)
Extend the provisions for password-protected entities to use the new
AccountModel.PubSharesPassManager to retain passwords within logins, and
from the non-authenticated state into logins.

Also, implement a functional interface to normalize getting and setting
passwords similarly across collections and models.
Use the new functional interface for getting and setting entity passwords.

Also, rectify the view finagling that's done after a valid password is
obtained, so that the share rooms root view still remains between the visit
into the passworded-shareroom's contents and the menu sheet.

That last part leaves a problem, where the share room root view is not
properly updated on resolution of the passworded-shareroom's metadata.  I'm
going to work on that next.
Improve the getShareRoomPasswordTemplate layout, and remove a debugging
initialize method left in FileModel.