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…

The task

**Public API.** Export `FluxKontextPipeline` from `diffusers`, `diffusers.pipelines`, and `diffusers.pipelines.flux`. Include a dummy stub for the class in `dummy_torch_and_transformers_objects.py`.

Part of FineEnvs/HF_ML_Tasksmith.