Add negotiated DNS servers to VPN config

This change plumbs the DNS servers through from the
IkeSessionConfiguration. Previously the getInternalDnsServer() was not
implemented.

Bug: 152242520
Test: FrameworksNetTests passing
Change-Id: Icd80b3688de2a39e222a4501787f8c54951c2ba0
Merged-In: Icd80b3688de2a39e222a4501787f8c54951c2ba0
(cherry picked from commit bd2763d977a4cad6f797f5378fc6db96e842dcf2)
1 file changed