ZSTD compression support

[sidorares]

currently only CLIENT_COMPRESS capability flag is supported ( inflate/deflate - https://www.rfc-editor.org/rfc/rfc1951.html )

when server sends CLIENT_ZSTD_COMPRESSION_ALGORITHM (1UL << 26) the client may elect to accept it

http://facebook.github.io/zstd/

https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_basic_compression.html
https://dev.mysql.com/doc/dev/mysql-server/latest/group__group__cs__capabilities__flags.html

looks like not in the node core, and most packages are compiled binary.
have as optional dependency and accept if installed?

https://github.com/mongodb-js/zstd

[dveeden]

Note that "Protocol::HandshakeResponse41" gets an extra field if CLIENT_ZSTD_COMPRESSION_ALGORITHM is set for the zstd_compression_level.