enhance: split response into chunks smaller than 2000 chars

[rodonguyen]

View issue #35

This PR:

• add split() in llm.py to split a string into smaller chunks less than 2000-char long
• iterate through the message list to send each element in bot.py

Result:

• example1
  
• example 2:
  
  

[rodonguyen]

@AndrewsTrinh why don't you replace my function with yours?
the project is pretty simple so I don't feel the need to split into another utils file. But up to you tho.

[AndrewsTrinh]

@AndrewsTrinh why don't you replace my function with yours? the project is pretty simple so I don't feel the need to split into another utils file. But up to you tho.
@rodonguyen : I just wanna keep it separated, so that you can review it and approve if it can be replacement to your function. I'm not really familiar with git workflow, just want to keep it there to makesure I'm not messing up something lol. I agree that due to simplity, separated utilities package is not necessary :)

[AndrewsTrinh]

@rodonguyen ready for review!