image embedding data cache

Description

tldr

reduce future unnecessary disk read for determining if an image is an image embedding or not
if addition option is enabled potentially reduce embedding load time by cacheing the embedding data

in embedding dir webui will scan and load image embedding

images that has textual inversion data embedded inside the image file

all png webp jxl avif in the dir will be considered as potential image embedding unless the image file name has a second suffix of preview webui will attempt to read and extract the textual inversion data from the image file this is a rather slow operation as it requires reading of the entire image from disk

if a user does not know about or forgot about image embedding (I don't think this is commonly used) they may decide to sotre extra image files that alongside the embedding file, like previews but don't have the .preview 2nd suffix if there are lots of images then they may found that loading embedded is taking exceedingly long

this happened to me, when I decided to dump lots of PNGs files that doesn't have .preview 2nd suffix into the embedded dir, took me some time to realize what happened

to solve this I use the diskcache from cache models to caching the results of loading an image as embedding this was able to drastically reduces the time that it takes to load the textual inversion

I implemented so that if an image is not an image embedding then the result is always cache, so next time it won't need to read from disk

if actual image embeddings won't be cached by default unless option textual_inversion_image_embedding_data_cache : Cache the data of image embeddings is enabled the reason why is an option is because even though I believe this reduce load time for the "actual image embedding" it will also takes up extra disk space

Notes:

I don't think I've done any changes that will cause things to break but I don't have any actual image embedding so this PR tested not teste with real data if someone that regularly use image embedding please verify this PR

Checklist:

[x] I have read contributing wiki page
[x] I have performed a self-review of my own code
[x] My code follows the style guidelines
[x] My code passes tests

AUTOMATIC1111 / stable-diffusion-webui