[NO ISSUE][API] Make QueryServiceServlet Extensible

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
- Change the visibility of QueryServiceServlet inner classes
  to allow extensibility.

Change-Id: I9c0e845bf45644fa103c3189259dd53778b7b228
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2589
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Murtadha Hubail <mhubail@apache.org>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Michael Blow <mblow@apache.org>
diff --git a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/QueryServiceServlet.java b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/QueryServiceServlet.java
index 714bb53..d22f657 100644
--- a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/QueryServiceServlet.java
+++ b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/QueryServiceServlet.java
@@ -196,7 +196,7 @@
         }
     }
 
-    static class RequestParameters {
+    protected static class RequestParameters {
         String host;
         String path;
         String statement;
@@ -241,7 +241,7 @@
         }
     }
 
-    static final class RequestExecutionState {
+    protected static final class RequestExecutionState {
         private long execStart = -1;
         private long execEnd = -1;
         private ResultStatus resultStatus = ResultStatus.SUCCESS;