cui: add a status indicator for the OLE insert dialog
Inserting a large file can take a while, and we do it on the main
thread, so the UI is frozen during the operation.
Create a statusbar and tell the user what's happening, even if the
underlying CreateObjectFromFile() and OleSave() functions don't report
their progress, so effectively this is more like a spinner than a
progressbar.
Change-Id: Ib5d90e214c556b43f170538fc152a9e27193773f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/122781
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins