* Fix JdbcSource handling of tables with same names in different schemas
* Previously the JdbcSource was combining the columns of any tables with the same name across different schemas into a single stream in the catalog.
* This was caught because in those tables there were columns of the same name with different types which triggered a precondition to check for this.
* The fix makes sure we group by both schema name and table name.
* Adds test to the standard jdbc tests to catch this case.
* This test does NOT run for mysql as, mysql has no concept of schemas.
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