Feat: Add Max Length Message Validation on File Upload's Description Input

[dhairyashiil]

As an EmbeddedChat developer

I need to: Implement character limit validation for the file description input field and display a warning message when the description exceeds the specified length.

So That: Users are notified when their file description exceeds the character limit, and it ensures better user experience by preventing errors during file upload.

Acceptance Criteria

• Add a maximum character limit for the file description.
• Display a warning message when the description exceeds the limit.
• The input field border and text color should change to indicate an error when the description is too long.
• Prevent file upload submission if the description exceeds the limit.

Refer RC: