SQL: JDBC: add support for a default catalog

[bpintea]

Some apps do not make use of JDBC's Connection#setCatalog API, but instead expect to be able to construct a connection string containing a default catalog and reinit a connection with the formed connection string every time the user selects a different catalog.
The connection string could look like es:jdbc://address:port/catalog?attr=value.

[elasticmachine]

Pinging @elastic/es-ql (Team:QL)

[costin]

👍 Worth looking at the various JDBC URLs out there to see whether there's a pattern for selecting the catalog (there are variants for selecting a database however that's not quite the same thing).

[bpintea]

This functionality is currently supported by using the catalog URL parameter (since #78903).
Note: the above suggested format won't work (backwards compatibly) given the path part of the URL (that is used in case ES is proxied under a specific path).