[Wi-Fi] Add intent action ＆ extra keys & result codes for add networks.

For supporting the mechanism for apps to add saved networks to the device, need to:
1. Add one new intent action.
2. Define two extra keys for passing data to Settings APP and get result
back.
3. Define 3 result codes.

Bug: 136472483
Test: just add action, test case will be in Settings App side.
Change-Id: I7391a6b8d89bd4621aab833b2da2a981f7b8163b