[client-v2] Writer API with custom insert statement.

[chernser]

Use case

Current Writer API implementation allows to write custom data stream. There is a case of writing DTO with less set of fields into a table. However there is no way to specify INSERT statement to do so. Currently, INSERT statement is sent via query.

Describe the solution you'd like

There should be options:

• set custom insert query
• let application decide where query should go - in the payload or HTTP query parameters

Describe the alternatives you've considered

Additional context

Relates: #2010

[den-crane]

Kinda obvious solution is to add one more method (though several overloaded) - "insertQuery"

insertQuery(String query, DataStreamWriter writer, ClickHouseFormat format, InsertSettings settings)

insertQuery(String query, DataStreamWriter writer, InsertSettings settings)

sqlStmt = query;

If format <> null then 
  String sqlStmt += " FORMAT " + format.name();

And use it like

response = client.insertQuery("insert into table(a,c,d)", out -> { }, ClickHouseFormat.JSONEachRow, insertSettings).get()

or

response = client.insertQuery("insert into table(a,c,d) format Parquet", out -> { }, insertSettings).get()