Update Codebase to use lastest OpenAI and Shiny API

[dar4datascience]

• Remove shiny experimental UI notation give that the functions used are available in the main python package
• changed notation of subcripting variables to using methods given that the openAI returns objects instead of nested lists.

[smach]

Hi @wch . Are there any plans to update chatstream to use more recent OpenAI API syntax as in this pull request, and to add current OpenAI models as Typed options? It's fine if not, but it would be helpful to know before I invest time in learning and coding with this. Thank you!!