ADD new enum NetworkType to identify multiple transport type

Add new NetworkType for multiple transport
1. CELLULAR + VPN = NT_CELLULAR_VPN
2. WIFI + VPN = NT_WIFI_VPN
3. BLUETOOTH + VPN = NT_BLUETOOTH_VPN
4. Ethernet + VPN = NT_ETHERNET_VPN

Bug: 143732914
Test: atest
Change-Id: I0d106ca1631265b872386b59d542b206614f38ef