Prevent TLEs from referencing other TLEs in requires

[olirice]

Description

We don't currently have dependency resolution in dbdev.

Currently, authors might specify requires in their control file to depend on other dbdev TLEs expecting that to work. It would be nice if we could detect and reject those projects on upload with a useful error message.

In the future, if we implement dependency resolutions, we can loosen that restriction.

Note: we still want to allow authors to define dependencies against native extensions (pgvector, hypopg, etc)

[olirice]

How will we detect TLEs vs non-TLEs

Since its an temporary measure until we get dependency resolution, how about creating an dependency allow list in the app schema and approve pre-installed extensions on any of the big providers Supabase/AWS/Azure/Google/Digital Ocean. Users can open issues if we miss anything.

We can reference that allow list when authors upload extensions