[Feature Request]: Unify function decorators for function calling, reply, termination and hook functions

[davorrunje]

Is your feature request related to a problem? Please describe.

Add function decorators for registering functions for reply, termination and hook and unify API

Describe the solution you'd like

Add the following function decorators:

@agent.register.for_execution
@agent.register.for_llm
@agent.register.for_reply
@agent.register.for_termination
@agent.register.for_hook

Additional context

No response