Write some JavaScript functional unit tests for existing code

[sbarber2]

Top-level issue for paying off our technical debt of not having unit tests for existing JavaScript files/modules. Setting a target of having all these done in the Dec2024 Milestone, supporting the release goal of "no big bugs."

Break it down by static/*.js file:

• audit.js unit tests #590
• planttracer.js first try: Movie list page needs Javascript testing #422 (in Oct2024 Milestone)
• planttracer.js (the rest) Movies list: more functional unit tests #559 Update jest tests to use common test data #585 Update jest tests to use common test data Part 2 #587
• canvas_controller.js unit tests #591
• canvas_movie_controller.js unit tests #592
• canvas_tracer_controller.js unit tests #593
• movie_stepper.js unit tests #594
• unzipit-worker.module.js unit tests #595
• unzipit.module.js unit tests #596