Allow EIMS Requests When No SIM is Active

-When there is no SIM, change the preferred
 data subscription to use phoneId=0 and to allow
 the EIMS / emergency NetworkRequest/APN type to
 go down to DcTracker.

-Always add the Emergency APN to the list of valid
 APNs:
--If no APN is found in the APNs DB construct one.
--After locating the emergency APN, immediately add
  it to the APNs list even if there is no SIM change,
  which occurs if the phone boots without a SIM.

Bug: 130663120
Test: atest PhoneSwitcherTest;
      atest TelephonyNetworkFactoryTest;
      manual verification by cp'ing: aosp/949940,
          aosp/946764, aosp/946998
Merged-In: I5b28527d96c3d7d3ee178cb54ffbe0027d10a2cd
Change-Id: I5b28527d96c3d7d3ee178cb54ffbe0027d10a2cd
(cherry picked from commit 1ff4b6ff)