Game Driver: update the format of driver build date

The string based driver build date has been updated to Unix epoch
timestamp based driver build time. This change updates the corresponding
apis and throw exceptions when the meta-data timestamp in the game
driver apk is not set properly.

Bug: 123156461
Test: Build, flash and boot. Verify the GpuService receiver side.
Change-Id: Id4fb3ade31fa5944dcb32fedf5ca926b497e82dc