Add support for new list of models

[icyavocado]

Add support for the new release of new 3.5 models: gpt-3.5-turbo, gpt-3.5-turbo-0613, gpt-3.5-turbo-16k, gpt-3.5-turbo-16k-0613

Implementation:

1. Add new models to the list of settings
2. Add settings for each models so that context token is dynamic instead of fixed at 4k tokens