feat(panel): make it possible to change the banner avatar or name of the bot from the panel

[Akinator31]

This pull request introduces a new API for viewing and updating the Discord bot's profile (username, avatar, and banner), along with supporting localization and UI changes. It adds backend endpoints, request handling, and base64 image parsing, as well as frontend internationalization and file handling improvements.

Backend: Discord Bot Profile API

• Added new API endpoints to get and update the bot's Discord profile (/profile) in the create_bot_router function, supporting both GET and PUT methods.
• Implemented handle_get_profile and handle_update_profile handlers in profile.rs to allow fetching and updating the bot's username, avatar, and banner, including validation and error handling.
• Added base64 image parsing for avatar and banner updates, supporting PNG, JPEG, GIF, and WebP formats.
• Registered the new module and exports in the bot handler module.
• Added base64 crate dependency for image decoding.

Frontend: Internationalization and File Handling

• Expanded English and French translation files to include all strings needed for the Discord profile editing interface.
• Extended web-sys features to support file and drag-and-drop handling in the frontend, preparing for image upload functionality.