Use highp precision for scaled coordination

If scaled coordination is closer to zero than what
the medium precision can store, distance becomes
zero and it causes divided by zero.

Change-Id: I8ee921dd1f57564a442e685266b12d95fc08e165
NetworkPolicy: Validate policy templates before updating

Ensure all the policies to be added are validated, otherwise
this service will throw IllegalArgumentException and cause
system crash when updating network template after receiving
ACTION_NETWORK_STATS_UPDATED.

Change-Id: I3faef0ac2a2fcea64ba5dde9c9256f6714280e2e
CRs-Fixed: 561490