MM: readd CreateMonitor handling

The mail merge wizard uses a different progress dialog
(CreateDialog) then the UNO functions (PrintDialog).

This restores the previously unused code and unifies some of the
dialog handling.

This reverts the dbmgr / mail merge unused code parts of
    commit d49d0139a7f4b9835a2179b6dcc6741a41b0197c and
    commit c16f45db0ea20db6ca3906551c01fb18f9258c84

Change-Id: I06088140f604893a33f3ee37507e551b043a193d
Reviewed-on: https://gerrit.libreoffice.org/10985
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>
Tested-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>