[FEATURE] Retrieve the original raw document via SQL (_source column)

[parked-toes]

Is your feature request related to a problem?
I need to retrieve the whole document, including arrays. When the result format is set to jdbc opensearch returns only 1st item from arrays. Using json format is not an option for me because a 3rd party driver I use, understands the jdbc format only.

What solution would you like?
Add support for _source meta column in column list expression part of SELECT statement.
e.g. SELECT _source, column1, column2 FROM ...

The _source column does not have be allowed in WHERE clause and functions.

Do you have any additional context?
Another metadata fields have been already added in this pull request:
#1456

[acarbonetto]

Returning the _source field in it's raw state is possible, but I see this as overkill for your problem.
Would adding array support like #1300 be sufficient for your case?

[parked-toes]

Yes, that would be sufficient