[ASTERIXDB-2303][API] Fix Supplementary Chars Printing

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

Details:
- Properly print supplementary chars as utf8
  by converting their java surrogates to a string.
- Add test case.

Change-Id: I59e825c11ff750d5b651fb86712023c52e98367e
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2429
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Michael Blow <mblow@apache.org>
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
index 4265163..9fc0b4b 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -6445,6 +6445,11 @@
         <output-dir compare="Text">varlen-encoding</output-dir>
       </compilation-unit>
     </test-case>
+    <test-case FilePath="string">
+      <compilation-unit name="utf8">
+        <output-dir compare="Text">utf8</output-dir>
+      </compilation-unit>
+    </test-case>
   </test-group>
   <test-group name="subquery">
     <test-case FilePath="subquery">