Replaced TelephonyNetworkFactory with TelephonyNetworkProvider

Adapted the new network provider model. The new TelephonyNetworkProvider
is a singleton responsible for providing all telephony related networks
including networks on cellular and IWLAN across all active SIMs.

Flag: com.android.internal.telephony.flags.support_network_provider
Fix: 343370895
Test: Comprehensive telephony tests including mobile data and voice call
      tests.
Test: atest TelephonyNetworkProviderTest
Change-Id: I99b236131606b83c2733a313715c313486b9a953