Support .pgpass file for passwordless connection in corporate/CI environments

[chirag127]

Problem

The PostgreSQL extension currently requires a password to be stored either in VS Code's secret storage (interactive only) or inline in the connection string. In corporate and CI environments, developers use a ~/.pgpass file (the standard PostgreSQL password file) to supply credentials without interactive prompts. The extension does not read .pgpass and instead always shows a password prompt or fails with authentication failed.

.pgpass format (for context)

# hostname:port:database:username:password
db.corp.example.com:5432:mydb:myuser:s3cr3t
*:5432:*:ci_runner:ci_password

File lives at ~/.pgpass (Unix) or %APPDATA%\postgresql\pgpass.conf (Windows). PostgreSQL's libpq reads it automatically, but the extension's custom connection logic bypasses it.

Steps to Reproduce

1. Create a valid ~/.pgpass (or %APPDATA%\postgresql\pgpass.conf on Windows).
2. In the extension, add a new connection with the matching host/port/db/user — leave password blank.
3. Click Connect.
4. Result: password authentication failed — extension never read .pgpass.

Expected Behaviour

Before prompting for a password, the extension should check .pgpass (standard location per OS) and use the matching entry if found. This aligns with psql/pg_dump CLI behaviour.

Proposed Implementation

• Add a utility resolvePgpass(host, port, db, user) that reads and parses .pgpass from the OS-appropriate location.
• Call it during connection before falling back to the password prompt.
• Add a pgsql.pgpassFile setting to override the default path (useful for CI where .pgpass is at a non-standard location).

Environment

• OS: Windows 11 Enterprise (path: %APPDATA%\postgresql\pgpass.conf) and Linux CI
• VS Code: 1.89+
• Extension: ms-ossdata.vscode-pgsql latest

[mmcfarland]

Thanks @chirag127 -- similar to #89, I may consolidate issues in the future, but I appreciate the extra signal that this is valuable.