Document the internal hook to build a result

Also change the arguments to be keyword arguments to make easier to
evolve this method if we need to.

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -739,7 +739,11 @@ def arel_visitor
         def build_statement_pool
         end
 
-        def build_result(columns, rows, column_types = {})
+        # Builds the result object.
+        #
+        # This is an internal hook to make possible connection adapters to build
+        # custom result objects with connection-specific data.
+        def build_result(columns:, rows:, column_types: {})
           ActiveRecord::Result.new(columns, rows, column_types)
         end
     end

activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb

@@ -54,17 +54,17 @@ def exec_query(sql, name = "SQL", binds = [], prepare: false)
           if without_prepared_statement?(binds)
             execute_and_free(sql, name) do |result|
               if result
-                build_result(result.fields, result.to_a)
+                build_result(columns: result.fields, rows: result.to_a)
               else
-                build_result([], [])
+                build_result(columns: [], rows: [])
               end
             end
           else
             exec_stmt_and_free(sql, name, binds, cache_stmt: prepare) do |_, result|
               if result
-                build_result(result.fields, result.to_a)
+                build_result(columns: result.fields, rows: result.to_a)
               else
-                build_result([], [])
+                build_result(columns: [], rows: [])
               end
             end
           end

activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb

@@ -103,7 +103,7 @@ def exec_query(sql, name = "SQL", binds = [], prepare: false)
               fmod  = result.fmod i
               types[fname] = get_oid_type(ftype, fmod, fname)
             end
-            build_result(fields, result.values, types)
+            build_result(columns: fields, rows: result.values, column_types: types)
           end
         end
 

activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb

@@ -63,7 +63,7 @@ def exec_query(sql, name = nil, binds = [], prepare: false)
                 records = stmt.to_a
               end
 
-              build_result(cols, records)
+              build_result(columns: cols, rows: records)
             end
           end
         end