Add Safety settings to vertex

Self Checks

[X] I have searched for existing issues search for existing issues, including closed ones.
[X] I confirm that I am using English to submit this report (我已阅读并同意 Language Policy).
[X] [FOR CHINESE USERS] 请务必使用英文提交 Issue，否则会被关闭。谢谢！:）
[X] Please do not modify this template :) and fill in all the required fields.

1. Is this request related to a challenge you're experiencing? Tell me about your story.

It would be great if for the model provider "Vertex AI" from Google Cloud, the safet settings would be added as an option:

"safetySettings": [
        {
            "category": "HARM_CATEGORY_HATE_SPEECH",
            "threshold": "BLOCK_LOW_AND_ABOVE"
        },
        {
            "category": "HARM_CATEGORY_DANGEROUS_CONTENT",
            "threshold": "BLOCK_LOW_AND_ABOVE"
        },
        {
            "category": "HARM_CATEGORY_SEXUALLY_EXPLICIT",
            "threshold": "BLOCK_LOW_AND_ABOVE"
        },
        {
            "category": "HARM_CATEGORY_HARASSMENT",
            "threshold": "BLOCK_LOW_AND_ABOVE"
        }
    ]

The default right now is no blocking, resulting in most users not being able to use it:

Bad Request Error, 400 User has requested a restricted HarmBlockThreshold setting BLOCK_NONE. You can get access either (a) through an allowlist via your Google account team, or (b) by switching your account type to monthly invoiced billing via this instruction: https://cloud.google.com/billing/docs/how-to/invoiced-billing.

2. Additional context or comments

No response

3. Can you help us with this feature?

[ ] I am interested in contributing to this feature.

langgenius / dify