Function change_user_name 

pub async fn change_user_name(
    virtual_file_system: &VirtualFileSystem,
    current_name: &str,
    new_name: &str,
) -> Result<()>

Changes a user’s username by updating their user file.

This function reads the user’s existing data, updates the name field, and writes the modified data back to the file system.

Arguments

• Virtual_file_system - Reference to the virtual file system
• Current_name - Current username of the account
• New_name - New username to assign

Returns

Returns Ok(()) if the username was changed successfully, or an appropriate error if the operation fails.

Errors

• File system errors (opening, reading, writing user file)
• JSON parsing errors
• Path construction failures