Stk: Add support for alpha in REFRESH command

RIL_UNSOL_STK_EVENT_NOTIFY is given by RIL in case there is alpha
id to be displayed to user in refresh proactive cmd.
Support is added to display Alpha id to user when this event comes
due to REFRESH proactive cmd.
Also if refresh mode is init or reset, idle mode text needs to be
cleared as per stk 3GPP spec 11.14. This logic is handled in stk
app to satisfy both the above requiremnts.

CRs-Fixed: 474693

Change-Id: Ic16da08d611753f2ee4a5b288f46b985078ca46f
(cherry picked from commit 0f67780941fca5d29643ffa2a55d087abee68484)
(cherry picked from commit 60e97197e74322b8deecf7135ec013b86708d16c)
(cherry picked from commit 83318f77647ed76250d1f2987513653bf98d99b9)