[ASTERIXDB-2449][FUN] Incorrect NULL/MISSING handling by concat functions

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

Details:
- Infer function return type as unknownable if
  its input list item can be NULL/MISSING
- Always return MISSING if there is a MISSING argument

Change-Id: Idc364b061f3e74bdc9d7715bbadedc957e9e8223
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2946
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@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 904dc61..04b484e 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -6619,6 +6619,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="string">
+      <compilation-unit name="string-concat2">
+        <output-dir compare="Text">string-concat2</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="string">
       <compilation-unit name="string-equal1">
         <output-dir compare="Text">string-equal1</output-dir>
       </compilation-unit>
@@ -9837,6 +9842,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="binary">
+      <compilation-unit name="concat2">
+        <output-dir compare="Text">concat2</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="binary">
       <compilation-unit name="subbinary">
         <output-dir compare="Text">subbinary</output-dir>
       </compilation-unit>