Add full support for UIDs in VPNs.

Major:
+ Implement the functions mentioned in http://go/android-multinetwork-routing
  correctly, including handling accept(), connect(), setNetworkForSocket()
  and protect() and supporting functions like canUserSelectNetwork().
+ Eliminate the old code path of getting/setting UID ranges through
  SecondaryTableController (which is currently unused) and mUidMap.

Minor:
+ Rename some methods/variables for clarity and consistency.
+ Moved some methods in .cpp files to match declaration order in the .h files.

Bug: 15409918
Change-Id: Ic6ce3646c58cf645db0d9a53cbeefdd7ffafff93
diff --git a/server/Network.cpp b/server/Network.cpp
index d22f42d..5104de2 100644
--- a/server/Network.cpp
+++ b/server/Network.cpp
@@ -25,6 +25,10 @@
     }
 }
 
+unsigned Network::getNetId() const {
+    return mNetId;
+}
+
 bool Network::hasInterface(const std::string& interface) const {
     return mInterfaces.find(interface) != mInterfaces.end();
 }