MdeModulePkg Ip4Dxe: Ip4Config2 to request DHCP Option6 DNS server IP

MdeModulePkg Ip4Dxe: Ip4Config2 to request DHCP Option6 DNS server IP

Ip4Config2 protocol implementation must request for DNS server info when the
policy is set to DHCP. And when a DHCP server responds to it with a list of
DNS server addresses, it must parse it and set it for the instance. Without
this, nobody can do a Ip4Config->GetData for DNS server IPs before calling
Dns->Configure(). This will mean a DHCP is initiated when calling
Dns->Configure(), thus causing serious performance issues. This patch
attempts to address this issue.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Samer El-Haj-Mahmoud <samer.el-haj-mahmoud@hpe.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Samer El-Haj-Mahmoud <elhaj@hpe.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18560 6f19259b-4bc3-4df7-8a09-765794883524