Feature request: Include tempory table schemas when a specific schema is attached

[echai58]

Is it possible to add support for accessing temporary tables when the SCHEMA parameter is used in ATTACH?

#259 is very nice to limit to attaching a single schema, but in doing so, duckdb no longer has access to the pg_temp_ schemas where temporary tables go.

#234 has been very useful too, so was wondering if there is some way to use temporary tables while maintaining the functionality from here (being able to query just in pg_temp schema) when a single schema is attached.