Add validation type definition to support multiple probe result

In order to allow NetworkMonitor to tell ConnectivityService
if the network is either parital, validated or both.
NetworkMonitor could update the probe result by passing the
bitmask to ConnectivityService.

Bug: 130078798
Bug: 130683832
Test: build
Change-Id: I429ccbd9b9afae3eafaf73b3c9eb835213c1f64d