NewConn: create connection with default server settings.

NewCustomizedConn: create connection with customized server settings.

NewDefaultServer: New mysql server with default settings.

NewServer: New mysql server with customized settings.

NewServerTLSConfig: generate TLS config for server side controlling the security level by authType.

Conn acts like a MySQL server connection, you can use MySQL client to communicate with it.

implements a in memory credential provider.

Defines a basic MySQL server with configs.

interface for user credential provider hint: can be extended for more functionality =================================IMPORTANT NOTE=============================== if the password in a third-party credential provider could be updated at runtime, we have to invalidate the caching for 'caching_sha2_password' by calling 'func (s *Server)InvalidateCache(string, string)'.