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/resolv/res_query.cpp b/resolv/res_query.cpp
index 0b46409..a9e4220 100644
--- a/resolv/res_query.cpp
+++ b/resolv/res_query.cpp
@@ -78,13 +78,14 @@
 #include <netinet/in.h>
 #include <sys/param.h>
 #include <sys/types.h>
-#include "resolv_cache.h"
-#include "resolv_private.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+#include "resolv_cache.h"
+#include "resolv_private.h"
+
 /* Options.  Leave them on. */
 #ifndef DEBUG
 #define DEBUG