Proxy PR for Long Context Capability 1513 (#1591)

* Add new capability to handle long context

* Make print conditional

* Remove superfluous comment

* Fix msg order

* Allow user to specify max_tokens

* Add ability to specify max_tokens per message; improve name

* Improve doc and readability

* Add tests

* Improve documentation and add tests per Erik and Chi's feedback

* Update notebook

* Update doc string of add to agents

* Improve doc string

* improve notebook

* Update github workflows for context handling

* Update docstring

* update notebook to use raw config list.

* Update contrib-openai.yml remove _target

* Fix code formatting

* Fix workflow file

* Update .github/workflows/contrib-openai.yml

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Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>
Co-authored-by: Chi Wang <wang.chi@microsoft.com>