Function format_duration 

pub fn format_duration(total_seconds: u32) -> String

Creates string representation as bytes, compatible with Erlang’s :erlang.integer_to_binary/1 Format a duration into human-readable form following the requirements:

• seconds if less than a minute
• minutes plus seconds if less than hour
• hours and minutes if less than day
• days and hours if less than month
• months and days if less than year
• years, months and days if bigger than year