Improve the PostgreSQL plugin by allowing to specify the target table schema

[nick-ivanov-edb]

Is your feature request related to a problem? Please describe.

Currently one can only create and/or reference a table to insert into in the default (public) schema, which is often discouraged or outright not allowed.

Describe the solution you'd like

We should have a configuration option to specify the schema where the target table is.

Describe alternatives you've considered

An alternative is to specify the search_path via connection options, but it's not obvious; we should have a more explicit configuration option for this common use case.

Additional context

A customer of ours tried to specify the table name that included the schema (like schema_name.table_name), because their policies (and general security best practices) don't allow creation of user objects in the public schema, and was surprised to see no rows inserted in that table. Instead, a table called public."schema_name.table_name" was created by the plugin and populated. We spent a lot of time trying to understand what's going on. Having an explicit table_schema configuration property would allow them to avoid the mistake and save the troubleshooting effort.