feat: add volcengine maas model provider

[sinomoe]

Description

add volcengine maas models provider

Fixes # (issue)

Type of Change

Please delete options that are not relevant.

• 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
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

How Has This Been Tested?

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

• self-host environment test

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods
• optional I have made corresponding changes to the documentation
• optional I have added tests that prove my fix is effective or that my feature works
• optional New and existing unit tests pass locally with my changes

[takatost]

Can you please add some integrate or unit tests?

[sinomoe]

Can you please add some integrate or unit tests?

sure

[sinomoe]

Can you please add some integrate or unit tests?

@takatost Integration test cases have been added

[takatost]

Can you please add some integrate or unit tests?

@takatost Integration test cases have been added

Thanks! We will review and test ASAP.

[takatost]

I haven't applied for the maas permission of Volcengine yet, but I have reviewed the code and found no issues. Thank you very much!

[crazywoola]

Hello please add my wechat crazyphage, I will invite you to our contributors' group.