javascript: Add direct TLS negotiation support to node-postgres sample

**Is your feature request related to a problem? Please describe.**
The node-postgres (pg) 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**
One the upstream driver supports the feature, modify the sample to add support for the `sslnegotiation` connection parameter.

**Describe alternatives you've considered**
- Using pg-native with a newer libpq version, but this requires additional platform dependencies and may have performance implications.

**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/brianc/node-postgres/issues/3346.

Check the upstream node-postgres issue 3346 first to confirm that direct TLS negotiation and the sslnegotiation connection parameter are supported. Then locate the node-postgres JavaScript sample and inspect how its connection parameters are passed. Done means the sample supports sslnegotiation without requiring pg-native, with the relevant sample verification passing.

Written by the indexing model from the issue text.