add new callback for scripts to be used before processing

add a way for scripts to register a callback for before/after just a single component's creation

add VAE from main model into infotext, not from refiner model
option to make scripts UI without gr.Group
fix inconsistencies with refiner when usings samplers that do more denoising than steps

Add postprocess_batch_list script callback

typo fix

split some code from ui.py into ui_settings.py ui_gradio_edxtensions.py
add before_process callback for scripts
add ability for alwayson scripts to specify section and let user reorder those sections

more stylistic changes

 - 1st webui, 2nd extensions-builtin, 3rd extensions
 - to load scripts independent of --data-dir
 - change load order key [x.basedir, x.filename, x.path] to [orderby(x.basedir), x.filename, x.path]

e.g., scripts/xyz_grid.py dependent extentions should loaded later
extensions\sd-webui-controlnet\scripts\xyz_grid_support.py
extensions\sd-webui-additional-networks\scripts\xyz_grid_support.py

 - 1st webui, 2nd extensions-builtin, 3rd extensions
 - to load scripts independent of --data-dir
 - change load order key [x.basedir, x.filename, x.path] to [orderby(x.basedir), x.filename, x.path]

e.g., scripts/xyz_grid.py dependent extentions should loaded later
extensions\sd-webui-controlnet\scripts\xyz_grid_support.py
extensions\sd-webui-additional-networks\scripts\xyz_grid_support.py