feat: Added SSH Tunnel for Postgres

[AnnaHariprasad5123]

@appsmithorg/contributor-support

Hi @rohan-arthur

Fixes #30792

Video Demonstration

What's in this pr :

• Added connection mode option for SSH Tunnel.
• Added SSH Host, Port, SSH Username and SSH key fields.
• Added Validation logic for SSH fields.
• Added SSH connection logic.
• Added three test cases for SSH connection.

Screenshots :

Please review this pr. Let me know if any changes required.

Summary by CodeRabbit

Summary by CodeRabbit

• New Features

  • Introduced SSH tunneling support for PostgreSQL connections, allowing users to configure SSH settings for enhanced security.
  • Added a new "Connection method" option in the configuration, enabling selection between "Standard" and "SSH tunnel" connections, with relevant fields for SSH details.

• Bug Fixes

  • Improved error handling by adding specific error messages for missing SSH configuration parameters, providing clearer feedback to users.

• Tests

  • Enhanced test coverage with new unit tests for validating the configuration of PostgreSQL data sources, particularly for SSH connections.