few more test cases for splitByChar

Author: bharatnc

tests/queries/0_stateless/02185_split_by_char.reference

@@ -1 +1,2 @@
 ['1','2','3']
+['1','2','3']

tests/queries/0_stateless/02185_split_by_char.sql

@@ -1 +1,6 @@
 select splitByChar(',', '1,2,3');
+select splitByChar('+', '1+2+3');
+-- splitByChar accepts only 1 byte length characters. Test for some special characters that are not necessarily single byte.
+select splitByChar('×', '1x2x3'); -- { serverError BAD_ARGUMENTS }
+select splitByChar('€', '€1,2,3'); -- { serverError BAD_ARGUMENTS }
+select splitByChar('•', '• 1,2,3'); -- { serverError BAD_ARGUMENTS }