Allow apps with SEND_SMS_NO_CONFIRMATION to bypass short code check.

Change SMSDispatcher to bypass SMS premium short code confirmation
dialog when caller has "android.permission.SEND_SMS_NO_CONFIRMATION"
permission (instead of checking package name against hardcoded list).

This permission is only available to system apps or those signed with
the same certificates as those in the system image.

Bug: 6502817
Change-Id: I6098d448892cc5e842ba6dc10cf494295e7226af