feat: image tools for gpustack

[alexcodelf]

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

Add gpustack image generation and edit tools.

2. Additional context or comments

No response

3. Can you help us with this feature?

• I am interested in contributing to this feature.

[alexcodelf]

GPUStack is an open-source GPU cluster manager for running LLMs. As we deployed image generation models locally, I am unable to integrate these models into Dify.

1. We want to use the image generation and edit feature in agent and workflow.
2. An auto-generate illustration application can be created with these tools.
3. Due to limited image data in some scenarios, we aim to generate additional data through text-to-image diffusion models with dify's workflow.