arc: Move platform2/arc/network/ to platform2/patchpanel

Next step in the arc-networkd -> patchpanel rename, this patch moves the
location of the code.

BUG=b:151879931
TEST=units,flashed image to atlas
TEST=tasts arc.PlayStore, crostini.LaunchTerminal.download

Change-Id: I1b5cf8d670e1631d46f6449b725395157bf88dde
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2115863
Tested-by: Garrick Evans <garrick@chromium.org>
Commit-Queue: Garrick Evans <garrick@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
Reviewed-by: Hugo Benichi <hugobenichi@google.com>
diff --git a/system-proxy/server_proxy.cc b/system-proxy/server_proxy.cc
index 2b720c8..a80f299 100644
--- a/system-proxy/server_proxy.cc
+++ b/system-proxy/server_proxy.cc
@@ -131,7 +131,7 @@
 }
 
 void ServerProxy::CreateListeningSocket() {
-  listening_fd_ = std::make_unique<arc_networkd::Socket>(
+  listening_fd_ = std::make_unique<patchpanel::Socket>(
       AF_INET, SOCK_STREAM | SOCK_NONBLOCK);
 
   struct sockaddr_in addr = {0};
@@ -185,7 +185,7 @@
 }
 
 void ServerProxy::OnConnectionSetupFinished(
-    std::unique_ptr<arc_networkd::SocketForwarder> fwd,
+    std::unique_ptr<patchpanel::SocketForwarder> fwd,
     ProxyConnectJob* connect_job) {
   if (fwd) {
     // The connection was set up successfully.