IMPALA-10918: Allow map type in SELECT list

Adding support for MAP types in the select list.
An example of how maps are printed:
{"k1":2,"k2":null}

Nested collection types (maps and arrays) are supported in any
combination. However, structs in collections and collections in structs
are not supported.

Limitations (other than map support) as described in the commit for
IMPALA-9498 still apply, the following are to be implemented later:
- Unify HS2 / Beeswax logic with the way STRUCTs are handled.
  This could be done in a "final" logic that can handle
  STRUCTS/ARRAYS nested to each other
- Implement "deep copy" and "deep serialize" for collections in BE.
  This would enable all operators, e.g. ORDER BY and UNION.

Testing:
 - modified the FE tests that checked that maps were not allowed in the
   select list - now the test expect maps are allowed there
 - added FE and EE tests involving maps based on the array tests

Change-Id: I921c647f1779add36e7f5df4ce6ca237dcfaf001
Reviewed-on: http://gerrit.cloudera.org:8080/18736
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>

testdata/workloads/functional-query/queries/QueryTest/nested-array-in-select-list.test

@@ -386,7 +386,7 @@ INT,INT,STRING
 ---- QUERY
 # Regression test for:
 #   IMPALA-11434: "More than 1 2d arrays in select list causes analysis error"
-select id, int_1d, int_2d, int_3d, string_1d, string_2d, string_3d from array_tbl;
+select id, arr_int_1d, arr_int_2d, arr_int_3d, arr_string_1d, arr_string_2d, arr_string_3d from collection_tbl;
 ---- RESULTS
 1,'[1,2,NULL]','[[1,2,NULL],[3]]','[[[1,2,NULL],[3]],[[4]]]','["1","2",NULL]','[["1","2",NULL],["3"]]','[[["1","2",NULL],["3"]],[["4"]]]'
 ---- TYPES