Improve performance when generating JSON schemas for plugin IDs

Translated using Weblate (Ukrainian)

Currently translated at 100.0% (343 of 343 strings)

Translation: Betty/Betty
Translate-URL: https://hosted.weblate.org/projects/betty/betty/uk/

Fix missing root paths for Webpack JS entry point assets (#2337)

Allow the image API to check if it supports a media type (#2308)

Add more information to the demonstration project (#2305)

Add generic *_plugin Jinja2 tests (#2285)

Fix an invalid PyPI classifier (#2281)

Extract functionality into an internal search API (#2280)

Fix a problem where fetched and cached images could not be resized by…

… allowing file caches to use file name suffixes

Fix mypy violations