javascript: Add direct TLS negotiation support to Postgres.js sample

**Is your feature request related to a problem? Please describe.**
The Postgres.js module currently doesn't support PostgreSQL 17's direct TLS negotiation feature. This feature improves connection performance and compatibility with certain proxies, but our codebase can't take advantage of it without driver support.

**Describe the solution you'd like**
Once the upstream driver supports the feature, modify the sample to add support for the `sslnegotiation` connection parameter.

**Describe alternatives you've considered**
- No alternative available.

**Additional context**
This feature was originally requested in #150 and has been broken out given many drivers already support this functionality.

Status upstream can be tracked in https://github.com/porsager/postgres/issues/993.

Start by checking the Postgres.js sample and the upstream driver status in porsager/postgres#993. Confirm that upstream support for PostgreSQL 17 direct TLS negotiation is available, then identify the sample's connection configuration and verify that the sslnegotiation parameter is accepted and demonstrated.

Written by the indexing model from the issue text.