[FEATURE] Add fields for the Initial SQL category in connection-fields.xml etc

[yurifal]

The optimal defaults for the Connection (session) could be pre-defined
and written in the Initial SQL right from the start (for every new Connection).

These could be done by adding one more "vendor" field in the connection-fields.xml
specifically for the Initial SQL category. There's no way to do it as of now
(such code would be ignored by xml parser).

Name: Yuri Fal
Company: Analytika Plus
What's in the making: http://github.com/analytikaplus/clickhouse-tableau-connector-jdbc

For example, I would like to define the following session parameter

SET join_use_nulls=1;

in the Initial SQL for every connection to ClickHouse --
for a proper results in the In/Out Set dimensions.

[jie-d]

Internal tracking id: 1320703

[VasanthiNeelagiri]

Hi, I am a new PM for the Connector SDK and I am looking at our feature backlog and getting things prioritized. I would appreciate if you can give your feedback for our product via this form. It should only take 2-5 mins but would be super valuable to our team. Thanks in advance!!
https://docs.google.com/forms/d/e/1FAIpQLSfs5OreNsxnva_uTO2vTxnoF-oq-37tEdrUpirUKwqud2Ib7g/viewform?usp=sf_link