Added Image Generation support

[ILYA-2606]

Description of the change

Add support for the Gemini Image Generation

Also fixed mime_type to mimeType for inlineData response field

Motivation

Fix of issue #220

Type of change

Feature request

Checklist

• I have performed a self-review of my code.
• I have added detailed comments to my code where applicable.
• I have verified that my change does not break existing code.
• My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• I am familiar with the Google Style Guide for the language I have coded in.
• I have read through the Contributing Guide and signed the Contributor License Agreement.

[adamroszyk]

Hey are you planning to update the sample UIs as well?
Thanks!

[printfMiaZhang]

Any updates for this? We still see the red cross mark here.