openai-examples module

[phelps-sg]

I have created a new module openai-examples which contains some of the examples from the README.md.

The motivation is to:

1. make it easier to get started with the library so users can run examples directly from their IDE without coding any boilerplate; and
2. ensure that all of the code in the examples can be easily be kept up to date as code in the library is improved and refactored, and to provide assurance that all the examples can be compiled and run at all times.

@peterbanda If you think this is a good idea, I will proceed to implement the complete set of examples from the readme.