Enable SD XL ONNX export and ONNX Runtime inference (#1168)
* add stable diffusion XL export
* fix style
* fix test model name
* fix style
* remove clip with projection from test
* change model name
* fix style
* remove need create pretrainedconfig
* fix style
* fix dummy input generation
* add saving second tokenzier when exporting a SD XL model
* fix style
* add SD XL pipeline
* fix style
* add test
* add watermarker
* fix style
* add watermark
* add test
* set default height width stable diffusion pipeline
* enable img2img task
* fix style
* enable to only have the second tokenizer and text encoder
* add test
* fix cli export
* adapt test for batch size > 1
