Support reevaluation request from captive portal app

CaptivePortalLogin use similar way to validate the network as
NetworkMonitor. Provide API to reuse NetworkMonitor facilities
for consistent captive portal detection.

Bug: 134892996
Test: atest FrameworksNetTests NetworkStackTests NetworkStackNextTests
Test: manually test with captive portal Wi-Fi
Test: make system-api-stubs-docs-update-current-api \
      test-api-stubs-docs-update-current-api
Change-Id: I6f039eae7ceb18eb6c3cf15587cdc27a7fe35b00