Use redirect URL to start webview

NetworkMonitor will detect captive portal and may get a redirect
URL from WiFi AP. Redirect URL should able to send to captive
portal app to open the webview instead of detecting again by
captive portal app.

Bug: 134892996
Test: Manually test with captive portal AP
Test: atest NetworkStackTests NetworkStackNextTests
Change-Id: Idf363c79b7243a899121be8a68b32d0541dff14f