Add EvaluatingBandwidthState to evaluate network bandwidth

Add a new state between EvaluatingPrivateDnsState and
ValidatedState to evaluate the network bandwidth.
This state is optional, OEMs can overlay the resource file and
set the related config to enable this feature.

Bug: 133522566
Test: atest NetworkStackTests
Change-Id: Ia2d6e4b8e434c15e76bc9e58874c40b1647f97fb