refactor(postgres): throw better error on connection fail

[ToBinio]

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [X] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

currently, if no connection can be established the error simply says

ECONNREFUSED: Failed to connect

When using db0 in e.g. Nitro this does not tell you a lot. With this PR the message looks like this:

ECONNREFUSED: Failed to connect - could not connect to Postgres DB at ""

this clearly tells you that something is wrong with your postgres db

📝 Checklist

• [ ] I have linked an issue or discussion.
• [ ] I have updated the documentation accordingly.

Note

currently, the connector in the postgresql.ts is called sqliteConnector. Which I don't think it should. If you agree let me know and I will quickly create a PR for it.