feat(cubesql): CONCAT function support for SQL push down

Author: paveltiunov

packages/cubejs-schema-compiler/src/adapter/BaseQuery.js

@@ -2423,6 +2423,7 @@ class BaseQuery {
         AVG: 'AVG({{ args_concat }})',
 
         COALESCE: 'COALESCE({{ args_concat }})',
+        CONCAT: 'CONCAT({{ args_concat }})',
       },
       statements: {
         select: 'SELECT {{ select_concat | map(attribute=\'aliased\') | join(\', \') }} \n' +

packages/cubejs-schema-compiler/src/adapter/PostgresQuery.js

@@ -49,6 +49,7 @@ export class PostgresQuery extends BaseQuery {
     // eslint-disable-next-line no-template-curly-in-string
     templates.params.param = '${{ param_index + 1 }}';
     templates.functions.DATETRUNC = 'DATE_TRUNC({{ args_concat }})';
+    templates.functions.CONCAT = 'CONCAT({% for arg in args %}CAST({{arg}} AS TEXT){% if not loop.last %},{% endif %}{% endfor %})';
     return templates;
   }
 }