Implement LAST_INSERT_IDS function (#1469)

Summary:
This is a multiple-value counterpart of the existing LAST_INSERT_ID function.
Its results are returned as a table.

- Hardcode the function name LAST_INSERT_IDS into the lexer and the parser due
  to how MySQL supports table-returning functions, patch the parser for the
  function.
- To keep the autoincrement value set efficiently, implement a data structure
  that 1) uses delta encoding for consecutive values; 2) special-cases encoding
  of consecutive delta equal to one values into a single number.
- Maintain the last_insert_ids set in THD for the previous and the current
  statement, similar to existing first_successful_insert_id_in_prev_stmt and
  first_successful_insert_id_in_cur_stmt fields.
- Add a main.last_insert_ids test.
- Since MyISAM is an engine that supports composite primary keys with
  autoincrement suffixes, this scenario is supported as well by allowing the
  values to be actually non-monotonic by delta encoding writing large deltas
  that make the value wrap around. For this case add a
  main.last_insert_ids_myisam test.

Pull Request resolved: #1469

Differential Revision: D60675155

fbshipit-source-id: c702048a14763db37140407c40f0d7ca648d5901

mysql-test/r/information_schema_keywords.result

@@ -314,6 +314,7 @@ KILL	1
 LAG	1
 LANGUAGE	0
 LAST	0
+LAST_INSERT_IDS	1
 LAST_VALUE	1
 LATERAL	1
 LEAD	1