Add Emergency Number Database version metrics

We need to add metrics for emergency number database version
In this metrics, we log emergency number db version when it
reaches to EmergencyNumberTracker, the phone process; this should
 verify whether the update is reaching phones.

Test: atest TelephonyMetrics
Bug: 146568709
Change-Id: I3c5ada8232f5fb3a4b10e397b6e7a64ae0b0cd88