Move resolver public headers to separate include path

Additionally rename functions and structs to eliminate those ugly
underscores from the public API (with the notable exception of
__res_params, which will come in its own separate change to keep this
one from growing too large).

Test: build, flash, then 'atest netd_integration_test'
Change-Id: I7e9b0ee6cdbec889e9c35b5a17b5daa65533686e
diff --git a/server/ClatdController.cpp b/server/ClatdController.cpp
index 9b357f9..1b54902 100644
--- a/server/ClatdController.cpp
+++ b/server/ClatdController.cpp
@@ -27,11 +27,10 @@
 #define LOG_TAG "ClatdController"
 #include <log/log.h>
 
-#include <resolv_netid.h>
-
 #include "Fwmark.h"
 #include "NetdConstants.h"
 #include "NetworkController.h"
+#include "netid_client.h"
 
 static const char* kClatdPath = "/system/bin/clatd";