Switch VpnDialogs from IConnectivityManager to IVpnManager.

The VPN code is moving out of ConnectivityService to a new
VpnManagerService. Update VpnDialogs to call into the new
service.

Bug: 173331190
Test: builds, boots
Test: atest HostsideVpnTests
Change-Id: I173ed0c3e39afb91c0dde1426dc492e9225afb00
3 files changed