Add postgresql-unit extension

[milutinovici]

What kind of change does this PR introduce?

Adds postgresql-unit extension

What is the current behavior?

Extension is not available for use

What is the new behavior?

Extension is available for use

Additional context

postgresql-unit implements a PostgreSQL datatype for SI units, plus byte. The eight base units can be combined to arbitrarily complex derived units using operators defined in the PostgreSQL type system

[brainrake]

needs to be added in more places, please use doc: https://github.com/supabase/postgres/blob/develop/nix/docs/adding-new-package.md

[brainrake]

Hi @milutinovici, thank you for the PR. Apologies for requesting changes earlier before making this call.

Unfortunately we can't accept new extension contributions right now: there's a freeze on adding extensions to the platform (see #1824), since each one carries a long-term maintenance, upgrade, and security commitment.

If you'd like to see postgresql-unit supported, please add it to https://github.com/orgs/supabase/discussions/679 so we can gauge demand. You can also fork this repo to build your own image for self-hosting.

Thanks again for contributing, and sorry we can't take this one. 🙏

[milutinovici]

Ok, no worries. I built the image for my own needs, thought I'd merge upstream.