Allow using praisonAI as library (non-CLI)

[jglaser]

Fabric (https://github.com/danielmiessler/fabric/tree/main) uses praisonAI as a library. However, praison parses the command line arguments in the main routine, which means that it takes takes fabrics's, which are incompatible with praison's. As a result, agent_file may get overwritten with other content.

https://github.com/danielmiessler/fabric/blob/45fcc547d53ecac2edf52f59f81a5e272cb28878/installer/client/cli/utils.py#L488-L490

praisonAI should only parse command line arguments when called from the command line. It would be nice if it provided an entry point so that it can be used as a library.