For historical reasons SQL restricts GROUP BY to only one field.
This commit removes the restriction and improves the test suite with
multi group by tests.
Close#31793
Significantly improve the example snippets in the documentation.
The examples are part of the test suite and checked nightly.
To help readability, the existing dataset was extended (test_emp renamed
to emp plus library).
Improve output of JDBC tests to be consistent with the CLI
Add lenient flag to JDBC asserts to allow type widening (a long is
equivalent to a integer as long as the value is the same).
This commit adds the ability to configure how a docvalue field should be
formatted, so that it would be possible eg. to return a date field
formatted as the number of milliseconds since Epoch.
Closes#27740
