Set is_upgrade flag before sending signal

Set is_upgrade flag before sending signal

There is no way to know whether a request type is "upgrade" when emitting signal
Installer can set upgrade flag before sending signal
and that flag is used to identify request type

Related change:
   [slp-pkgmgr] https://review.tizen.org/gerrit/#/c/platform/core/appfw/slp-pkgmgr/+/237961/
   [slp-pkgmgr] https://review.tizen.org/gerrit/#/c/platform/core/appfw/slp-pkgmgr/+/238789/

Change-Id: Ifcd05d766bd69422c0e7397bad7484282ec2f2b2
Signed-off-by: Ilho Kim <ilho159.kim@samsung.com>