Web UI: Gallery improvements

[psychedelicious]

• Reverts the masonry style layout, fixes WebUI - gallery refresh performance #1053
• Moves the small below-image hover buttons to a context menu, with delete also appearing at corner of the image, fixes Web UI: Unable to reach gallery buttons if image has no metadata #1182
• Adds toasts as visual feedback gallery actions
• Updates postprocessing WIP tab verbiage
• Improves handling of scenario where an initial image was deleted but user attempts to use it as initial image
• Fix for In invoke web UI, pressing "Use All" on a txt2img does not change web UI state to indicate change to txt2img #1102

The context menu is a Radix UI component. I started making my own but realized the scope of handling everything, and searched for a library to use.

One of the first and most promising results was a Radix UI component, and as I was already leaning towards Radix decided to use it. Works nicely.

[blessedcoolant]

A couple of changes:

1. The background hover color in dark mode on the right click panel is too similar to the base color. Needs to be lighter.
2. Change the cursor to pointer on the right click menu too.
3. Add a bit of spacing between the right click elements so they dont look like a block of text.
4. Setting use all Parameters unsets the init image breaking the display. Use all Parameters should not apply init_image at all.

[psychedelicious]

@blessedcoolant
Updated styling.

We should set the init image if one was used... However I can replicate what I think is the issue you had, if the init image no longer exists.

To address this, we need to allow the image to attempt to load. Then use the onError listener to un-set the init image when it fails, popping a toast in that situation.

Does that fix the issue you ran into?

[psychedelicious]

updated changes in first post.