Add FluxKontextPipeline to the diffusers library as an image-conditioned Flux denoising pipeline for…

Add FluxKontextPipeline to the diffusers library as an image-conditioned Flux denoising pipeline for…: a task in HF ML Tasksmith (Harbor dataset). Public API. Export FluxKontextPipeline from diffusers , diffusers.pipelines , and diffusers.pipelines.flux . Include a dummy stub for the class in…