Improve closing investment accounts

One needed to close all security accounts first before one could close
the parent investment account. This change improves the process so that
an investment account can be closed with all sub-ordinate security
accounts in one go if the conditions to close an account apply to all
accounts to be closed (balance equal to zero, not referenced in
schedules, ...)

CCBUG: 450927
(cherry picked from commit b17daebd)