[Feature Request] Integrate Lexica API for importing AI character portraits

[apoapostolov]

Docs: https://lexica.art/docs

This feature will add a new button on the Avatar side that will open a new dialog that contains a search field for searching Lexica. The window is populated with thumbnails of all results found for that search, up to an acceptable maximum. Button to page the results left and right if not all results can be displayed on the screen. Click on a picture to import the large image in the Avatar pane.

Settings to ignore NSFW results (on by default)