Implement PartitionClause::modify_schema in the same way as the others

Author: alexowens90

cpp/arcticdb/processing/clause.hpp

@@ -273,14 +273,14 @@ struct PartitionClause {
     }
 
     OutputSchema modify_schema(OutputSchema&& output_schema) const {
-        // TODO: Factor out checking against clause_info_.input_columns_ into separate function and call from all clauses
-        // TODO: Consider adding (optional, lazily constructed?) unordered map from column names to data types in
-        //  output_schema to make this sort of operation more efficient
-        schema::check<ErrorCode::E_COLUMN_DOESNT_EXIST>(
-                output_schema.stream_descriptor_.find_field(grouping_column_).has_value(),
-                "GroupByClause requires column '{}' to exist in input data",
-                grouping_column_
-        );
+        const auto& column_types = output_schema.column_types();
+        for (const auto& input_column: *clause_info_.input_columns_) {
+            schema::check<ErrorCode::E_COLUMN_DOESNT_EXIST>(
+                    column_types.contains(input_column),
+                    "GroupByClause requires column '{}' to exist in input data",
+                    grouping_column_
+            );
+        }
         return output_schema;
     }