1. support SHOW LAST INSERT
In the current implementation, the insert operation returns a json string to describe the result information
of the insert. But this information is in the session track field of the mysql protocol,
and it is difficult to obtain programmatically.
Therefore, I provide a new syntax `show last insert` to explicitly obtain the result of the latest insert operation,
and return a normal query result set to facilitate the user to obtain the result information of the insert.
2. the `ReturnRows` field in fe.audit.log of insert operation will be set to the loaded row num of the insert.
3. Fix a bug described in #8354
1e70f992e7