Remove max width for model dropdown

not clear checkpoints cache when config changes

Fix remove `textual inversion` prompt

Removing the max width for the model dropdown allows the user to see the full name of a model especially when it is long.
Model names are getting more complex and longer and the current width almost always cuts off model names.
If a user leverages folders than it pretty much always cuts off the name...

update extensions table: show branch, show date in separate column, and show version from tags if available

load extensions' git metadata in parallel to loading the main program to save a ton of time during startup

Add GPU device

launch.py: Don't involve shell for running Python or getting Git output

Fixes Linux regression in 451d255b

fix xyz checkpoint

Add GPU option to troubleshoot.

Files in vae folder with same name as a checkpoint can be found too

allow jpeg for extra network preview

add a bit of spacing/styling to settings elements
add link info for token merging

Integrate optional speed and memory improvements by token merging (via dbolya/tomesd)

Add/modify CFG callbacks for Self-Attention Guidance extension

Bump some versions to avoid downgrading them

Required by self-attn guidance extension
https://github.com/ashen-sensored/sd_webui_SAG