[feature] Support LOCAL INFILE

[mirromutth]

Is your feature request related to a problem? Please describe.

Currently, we have Capability.LOCAL_FILES marked as disabled, and it is not actually supported. The statement like following:

LOAD DATA LOCAL INFILE '/path/to/file' INTO TABLE `my_table`; 

After executing this statement (without error), the database server will immediately request the file content from the driver.

Note: MySQL 8.0+ has @@global.local_infiles disabled for security reasons, so this feature should be disabled by default.

Describe the solution you'd like

• Add a LocalInfileRequest to package message.server, the header is 0xFB
• Add a LocalInfileResponse to package message.client, each such message contains a file chunk or an empty chunk (means End-Of-File)
• Add LOCAL INFILE support in message decoder
• Add LOCAL INFILE support in QueryFlow, which should send file chunks and an empty chunk after receiving LocalInfileRequest
• Maybe add an option for specifying the max size of file chunk

Additional context

See also MySQL and MariaDB docs

It is only supported in text protocol queries.

Reference from: mirromutth/r2dbc-mysql#110