DALL·E 3 support

[enricoros]

Support DALL·E 3 as an alternative to Prodia for image generation.

Requirements:

• Add backend functions for image generation
• Fully support DALL·E 3 API options (wire types, etc)
• Output to both Base64 or URLs
• Architecture
  • abstract Prodia image generation into a general architecture
  • have a list of image-generation models
  • multiple OpenAI vendors are supported, so get ready for multiple models
  • if more than 1 model in the list, the right model ref should be picked in the configurator
• Configuration of all the Image generation models in the "Draw" part of the configurator
  • all options supported by Dalle should be available to set globally in this portion of the UI
  • (but the client code should support overriding global configuration options on a per-call level)
• Use the active image generation model where Prodia is used today

[enricoros]

Settings Dialog

All options, including a cost preview:

Generation, including the re-written OpenAI Dall-E prompt, on hover: