R2DBC - fake transaction requirement.

[rernas35]

This reminds that probably we need to promote FakeTransaction from clickhouse-jdbc to clickhouse-client, so that it can be reused in R2DBC as well. This is something we need to refactor in the future. QueryManager / RequestManager should be added as well so that user has the ability to manage query/session id generation as well.

https://github.com/rernas35/clickhouse-jdbc/blob/41e1afc89c4c5aa6c1e6874148545086deca9d06/clickhouse-r2dbc/src/main/java/com/clickhouse/r2dbc/connection/ClickHouseConnection.java#L48