Add next page navigation for RDAP nameserver searches

Domain and entity searches will be handled in future CLs.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=178912832

java/google/registry/request/RequestModule.java

@@ -84,6 +84,12 @@ public final class RequestModule {
     return authResult;
   }
 
+  @Provides
+  @RequestUrl
+  static String provideRequestUrl(HttpServletRequest req) {
+    return req.getRequestURL().toString();
+  }
+
   @Provides
   @RequestPath
   static String provideRequestPath(HttpServletRequest req) {