Query log: add support for logging prepared statement parameters

[renecannao]

This is related to #3687

We need to add parameters when logging prepared statement.

Logging must be for both binary format and json format.

Splitting the issue into subteasks

All logging types

• 4861-all: define the list of all MySQL data types
• 4861-all: identify the most efficient way to achieve parameters logging without unnecessary overhead (new classes, data copy, etc)

for binary logging

• 4861-binary : evaluate the best logging format , probably matching MySQL protocol format
• 4861-binary : define the format for each MySQL data types
• 4861-binary : implement logging of parameters received with COM_STMT_EXECUTE
• 4861-binary : implement logging of parameters received with COM_STMT_SEND_LONG_DATA
• 4861-binary : implement testing for each MySQL data types received via COM_STMT_EXECUTE
• 4861-binary : implement testing for "long" MySQL data types received via COM_STMT_SEND_LONG_DATA
• 4861-binary : implement testing of mixing data types received via COM_STMT_EXECUTE and COM_STMT_SEND_LONG_DATA
• 4861-binary : document in detail the new logging format

for JSON logging

• 4861-JSON : define the format for each MySQL data types
• 4861-JSON : implement logging of parameters received with COM_STMT_EXECUTE
• 4861-JSON : implement logging of parameters received with COM_STMT_SEND_LONG_DATA
• 4861-JSON : implement testing for each MySQL data types received via COM_STMT_EXECUTE
• 4861-JSON : implement testing for "long" MySQL data types received via COM_STMT_SEND_LONG_DATA
• 4861-JSON : implement testing of mixing data types received via COM_STMT_EXECUTE and COM_STMT_SEND_LONG_DATA
• 4861-JSON : document the extension to JSON format

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Notes:

On COM_STMT_SEND_LONG_DATA

Although ProxySQL handles commands COM_STMT_SEND_LONG_DATA received from the client, it efficiently only uses COM_STMT_EXECUTE when executing prepared statements to the backend, reducing the number of network round trips.

Data received via COM_STMT_SEND_LONG_DATA is stored in a StmtLongDataHandler object .
When ProxySQL receives a COM_STMT_EXECUTE , in MySQL_Protocol::get_binds_from_pkt() it also retrieves the data in the StmtLongDataHandler object . This should mean that we shouldn't scan the StmtLongDataHandler object for parameters.