Enable authentication to Postgres on Azure using Entra ID

Currently, it is not possible to connect to Postgres running on Azure via Entra ID.

When using psql, the usual way is to export PGPASSWORD from az-cli.

```
  export PGPASSWORD=$(az account get-access-token --resource-type oss-rdbms --query accessToken -o tsv)
```

It would be nice if there is a way to implement passwordless connection in sqlit (if needed, I can try submitting a PR)