Function Calling Support for Gemini - Part 2 (#3726)

* Added function calling support to GeminiClient

* Appending a continue message from model to alternate between user and model

* Fixed cost calculation to include <128K costing and new 1.5-flash model. Added test case for function_call.

* Add notebook with samples for Gemini

* Updated test case

* Fix to handle not dict response in function call

* Handle non dict function results and append dummy model message between function response and user message

* Fixing message order in gemini

* Append text as multiple parts instead of test concatenation

* Raising error for Union data types in function parameter

* Delete default key

* Update gemini.py for multiple tool calls + pre-commit formatting

* no function role

* start adding function calling config

* do not serialize tool_config

* improve tool config parsing

* add hint

* improve function calling config

* removunnecessary comments

* try removing allowed function names in tool config conversion

* fix tool config parsing with empty tools list

* improve logging and case handling with vertexai tool config parsing

* reset file

* check if text is in part

* fix empty part checking case

* fix bug with attribute handling

* skip test if gemini deps are not installed

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Co-authored-by: Arjun G <arjun@arjun-g.com>
Co-authored-by: Beibin Li <BeibinLi@users.noreply.github.com>
Co-authored-by: Chi Wang <wang.chi@microsoft.com>
Co-authored-by: Mark Sze <66362098+marklysze@users.noreply.github.com>