Add audit logging for more MySQL commands

[greedy52]

Added parsing and audit logs for the follow commands:

• COM_INIT_DB: switch database
• COM_CREATE_DB: create database
• COM_DROP_DB: drop database
• COM_REFRESH: sends "FLUSH" or "RESET" commands
• COM_SHUTDOWN: shuts down mysql server
• COM_PROCESS_KILL: ask the server to terminate a connection
• COM_DEBUG: forces the server to print debug info to stdout (on server side)

Testing:

• Tested COM_INIT_DB by USE users from tsh db connect (users is a schema/database)

• Tested COM_PROCESS_KILL with mariadb python client

Other commands are mostly deprecated so very hard to find a client to compose them.

[r0mant]

@greedy52 Nice job! Don't forget to update webassets accordingly to support these new event types pls.