[Feature] Improve the texture creation modal

[3vorp]

Is your feature request related to a problem?

The texture creation modal is currently very cramped, ugly, and confusing.

Describe the feature you'd like

To mitigate the sheer amount of fields needed for adding several textures at once, I suggest that the new texture modal instead fill the entire screen and have one tab for each texture. This way, you don't end up with a ton of vertical layers, plus with a wider layout uses and paths can be represented more cleanly instead of being simply indented (I like how the add-on form handles downloads).

I was thinking of implementing this feature similarly to the gallery modal, where instead of a new page there's a fullscreen modal (this should help reduce redirects and make it easier to implement over a full page).

Screenshot(s)

I didn't include it here, but I figured the JSON converter could be a button on the top right or something simple, as it's not used super often and doesn't need to take half of your screen. I was also thinking of maybe making a JSON serializer for the modal and using browser localstorage to add the ability to store and retrieve texture drafts.

Notes

Parts of this were suggested by Rolf at one point for an overhaul of the texture edit modals, but I feel like having smaller modals works better there since it makes it easier to edit small things (which is what the texture edit modals are mostly used for) and makes the request size smaller since you're only making a request to edit the specific use, path, or base texture json with only that data.

I also feel like this should also go alongside an overhaul of the API backend—it's consistently broken in some way or the other as seen in #138 and #115 and I think a new modal would nicely facilitate some code cleanup.

[3vorp]

was testing some vuetify stuff out in codepen and I think this timeline style interface would work really nicely with uses/paths https://codepen.io/Evorp/pen/PorgozE