feat: Add general IDE info to User-Agent for Tabby clients

[Sma1lboy]

This addresses the remaining part of the issue mentioned in #2581.

• Retrieve client info based on the client configuration during client initialization.

Example User-Agent format:

Node.js/v20.9.0 Visual-Studio-Code-desktop/1.91.1 TabbyML.vscode-tabby/1.8.0-dev