Added video calling data usage per-uid support

Now the VT call data usage will be counted under
current dialer's data usage as well as the total
device data usage.

Test: Manual
bug: 37671326

Merged-Id: Ic7a87bf816bb12f1be9d66ee9aafb54174df0235
Change-Id: Ic7a87bf816bb12f1be9d66ee9aafb54174df0235