Feature Request: allow a callback function to be passed as the function used in the human input tool

[tomlynchRNA]

i.e allow users to replace this function: https://github.com/joaomdmoura/crewAI/blob/3d5257592b440fca8c46b77471e1c34c901ee57f/src/crewai/agents/executor.py#L298

I would change the contents to pull the human input from another system instead of just calling input(). Happy to make a PR, shouldn't be a huge change. Would this be something that would be accepted?