Add SambaNova support

[rodrigo-92]

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.

I work for SambaNova https://sambanova.ai/ and we're eager to integrate our LLMs in Dify. We'd like to include first an integration to SambaNova Cloud https://cloud.sambanova.ai/

2. Additional context or comments

no additional context

3. Can you help us with this feature?

• [X] I am interested in contributing to this feature.