General Changes

• Add support for calling connector-defined procedures using CALL.
• Add System Connector procedure for killing running queries.
• Properly expire idle transactions that consist of just the start transaction statement and nothing else.
• Fix possible deadlock in worker communication when task restart is detected.
• Performance improvements for aggregations on dictionary encoded data. This optimization is turned off by default. It can be configured via the optimizer.dictionary-aggregation config property or the dictionary_aggregation session property.
• Fix race which could cause queries to fail when using concat() on ARRAY, or when enabling columnar_processing_dictionary.
• Add sticky headers and the ability to sort the tasks table on the query page in the web interface.