IpConnectivity metrics: add version number

This patch adds a version field to ipconnectivity.proto and populates it
to 2, which is the logical version number for NYC-MR2.

Test: IpConnectivity{EventBuilder,Metrics}Test pass
Bug: 32127906
Change-Id: I1439f012b7f9b4211d5d5429c274ad03d2ac9d6b
5 files changed