Route parameter $image_style upcast as entity in core 9.5

Problem/Motivation

This module no longer works in core 9.5, the issue being the route parameter $image_style is now passed as an entity and not a string - this means any dynamic image style URLs serve a 404 since there's no defined image style entity with that ID.

Steps to reproduce

Upgrade to core 9.5, dynamic image styles serve 404 (even with empty allowed_image_styles config).

Proposed resolution

Attached patch uses a custom ParameterConverter to either load defined image styles or create a dynamic one before passing to the route controller.

NB the patch also contains changes made by patches in the issues to upgrade info file for D9 ( https://www.drupal.org/project/image_style_dynamic/issues/3139308 → ), and to allow regex in allowed image styles config ( https://www.drupal.org/project/image_style_dynamic/issues/3223708 → ).

Remaining tasks

QA.