Improving Director Engine Compatibility and Tooling

The ScummVM Director engine supports a number of games built with Macromedia Director, but many still have bugs or missing features. This project improves the engine across four areas: (1) enhancing the ImGui visual debugger with crash fixes, missing cast detail views, and search improvements, (2) completing Filmloops and Movie Cast Members for games like TrekTech, Gus (3) fixing bugs in Gus Goes to the Kooky Carnival and The Journeyman Project, and (4) getting the screenshot regression tool working for automated visual testing on the buildbot. If these tasks finished early, I will work on other incomplete Director engine features and fix bugs.