Add VTS for emergencyDial

Modify the document for 'hasKnownUserIntentEmergency'.

In the scenarios that the 'address' in the 'dialInfo' field has other
 functions besides the emergency number function, if the
 'hasKnownUserIntentEmergency' field is true, the user's intent for this
 dial request is emergency call, and the modem must treat this as an
 actual emergency dial; if the 'hasKnownUserIntentEmergency' field is
 false, Android does not know user's intent for this call.

Test: compile
Bug: 121345950
Change-Id: I3457e7519be564ac5043e06380e9450a1b12425f
(cherry picked from commit 7208840ec0148ad5a01bdf419170282cd1b32437)