Add LessonEditorDialog React Component

[Hamms]

We have a bunch of dialogs in the lesson editor that were all making identical customizations to the BaseDialog component. I extracted all that into a single LessonEditorDialog component, and updated the components to use it instead.

Also organized a few import statements.

Testing story

Updated a number of tests which apparently care about which specific component we're using to render dialogs. Also had a conversation with Dave about rethinking our approach to testing moving forward.

Reviewer Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked