Add initialize db function for smoke test

Add initialize db function for smoke test

After below patch
   https://review.tizen.org/gerrit/#/c/platform/core/appfw/pkgmgr-info/+/207513/
The smoke test requires the process of creatring db for testing.
This is because opening the db with the "SQLITE_OPEN_READWRITE" flag doesn't create a db.

Related changes
   [tpk-backend] https://review.tizen.org/gerrit/#/c/platform/core/appfw/tpk-backend/+/210255/
   [wgt-backend] https://review.tizen.org/gerrit/#/c/platform/core/appfw/wgt-backend/+/210254/

Change-Id: I16161eba7b8b649a7e912891def3b81c1dc6dff6
Signed-off-by: Ilho Kim <ilho159.kim@samsung.com>