Update serialization on the batch images endpoint

Also minor refactor

It didn't make sense to have two differente files for the same and
"models" is a more descriptive name.

In batch mode run_extras tries to preserve the original file name of the
images. The problem is that this makes no sense since the user only gets
a list of images in the UI, trying to manually save them shows that this
images have random temp names. Also, trying to keep "orig_name" in the
API is a hassle that adds complexity to the consuming UI since the
client has to use (or emulate) an input (type=file) element in a form.
Using the normal file name not only doesn't change the output and
functionality in the original UI but also helps keep the API simple.

update ESRGAN architecture and model to support all ESRGAN models

 - Separate extra modes into 3 endpoints so the user ddoesn't ahve to
handle so many unused parameters.
 - Add response model for codumentation

Someone had 6000 images in their dataset, and it was shown as 0, which was confusing.
This will allow tracking real time dataset-average loss for registered objects.

added an option to always only show one image in previews
removed duplicate code

[Hypernetworks] Add a feature to use dropout / more activation functions