Switch from replacement scans to using catalogs

[Mytherin]

• This allows us to insert into tables by defining a custom insert operator
• This makes schemas work natively without needing the current work-around

[Tishj]

This issue would be fixed as a side-effect

[Tishj]

This issue would be fixed as a side-effect

Little update on this: it won't be entirely fixed by this, DuckDB has some limitations on bindings, and with this change we have less control over aliasing to work around those so this will eventually need to be fixed upstream

SELECT count(*) FROM public.t, other.t; will fail as both public.t and other.t will be aliased as t We previously worked around this limitation by aliasing as "public.t" and "other.t"

[JelteF]

Closing this since #97 was merged