chore: massive update of the Gemini models based on latest documentation

[CXwudi]

Checklist:

[!IMPORTANT]
Please review the checklist below before submitting your pull request.

• [x] Please open an issue before creating a PR or link to an existing issue
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas (no code changes)
• [x] I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods (no code changes)

Description

Fixes #8821.

Also, based on the documentation, "Latest" and "Latest Stable" models are two different versions. Hence, I also separated the gemini-1.5-pro away from gemini-1.5-pro-latest. Likewise for flash models.

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update, included: Dify Document
• [x] Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• [ ] Dependency upgrade

Testing Instructions

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [x] Test several new models in various scenarios, such as Agent + Function calling, Workflow, etc.

[crazywoola]

Hello can you take a look at this feature as well? https://github.com/langgenius/dify/issues/8805

[CXwudi]

Hello can you take a look at this feature as well? #8805

Hi, I could try, but I am not familiar with Dify codebase, so please don't bet on me.

[CXwudi]

@crazywoola About the request of https://github.com/langgenius/dify/issues/8805, are you referring to https://github.com/langgenius/dify/pull/8721 which simply just remove the harm category setting, but this time you want me to do it for Gemini endpoints?

If that so, I believe that is simply just removing:

https://github.com/langgenius/dify/blob/main/api/core/model_runtime/model_providers/google/llm/llm.py#L209-L214

Correct? If so, then I think I can do that