[Settings] Adjusted the API of Settings app

The API of Settings app get changed in order to support large screen.
This is a fix to adopt the change related to this work.

A short brief:
1. Accept ACTION_MAIN for launching MobileNetworkActivity.
2. Support deep-link intent while MobileNetworkActivity in foreground.
3. Avoid from binding MobileNetworkActivity as a single instance.

Bug: 230047450
Bug: 234406562
Bug: 229371407
Test: local & unittest
Change-Id: Ifcb9d4c564839199d998bd503f390f021c6bf3ad