Add support for gemini chat

Add the class LLMAPIChatGemini to use gemini AI with the compatibility layer

It is a specific class because Google decided to not use the exact same API

v1.0.2

Make default model for chat in setting

v1.0.1

consolidate API

v1.0.0 - force stabilize API

This is a release to force @badetitou stop breaking everything

Full Changelog: https://github.com/Evref-BL/Pharo-LLMAPI/commits/v1.0.0