Cut pow/resume and postprocess video

resume option in gradio notebook
- Default behaviour is the same -- all generated frames from the previous run will be deleted when press render button. But if resume option is selected, the animation will be continued from the last existing frame if resume_from=-1, or any specific positive frame number.
- These two parameters are the first one in the Input tab, because they kind of overwrite init image, but it's up for discussion
Postprocessing can be done for any specified videofile
- Frames are extracted to a 'frames' subdirectory near the videofile; then processed just like a generated frames project dir.
- I've decided to go with videofiles and not directories because it's more universal and a directory way obliges to have specific image name format in it.
- This is also the first two options in the Post tab because it is input, but it's also up for a discussion.
- Gradio components File and UploadButton allow to use file manager to navigate to a video instead of specifying its path, but for some reason they both were freezing the notebook rendering for me. I haven't tried running it in colab, and haven't played around it much, but decided to go for a simpler (although a bit less convenient) solution, especially since the video_input_path is a Text also.
upscale frames in correct order

Stability-AI / stability-sdk