[Wi-Fi] Add proto fields for Openroaming network.

Add two new proto fields for Openroaming network use.

In settings -> Network and Internet -> Wi-Fi, user may click on an Openroaming Wi-Fi AP for Wi-Fi service, so need to add two metrics to record this behavior:
1. OPENROAMING_TAP: records when user tap on the Openroaming Wi-Fi.
2. OPENROAMING_TAP_ON_WIFI_CONNECTION: records when user alreay connected to any wi-Fi network but still tap on the Openroaming Wi-Fi to change to Openroaming.

Bug: 146669261
Test: No, just add proto fields.
Change-Id: If203761052646e3a9df6e9a76fd5268c3db965fd