Phone: Ignore touch during network operators search

When network search is in progress, the progress dialog is
dismissed if user taps the screen. This in-turn cancels
manual search and switches to the previous screen.
This behavior can be avoided if the dialog property is set
to ignore user touch events.
If required BACK key can be used to cancel search and move
to previous screen.

Change-Id: I00da1dfec78498d2f35f6bb5d49e42bb3ad43cc2
CRs-Fixed: 367631