Figure out if these can become Sectors or if they need to be Categories or an entirely new model

Currently serviced via wordpress: https://stories.awbw.org/share/ (pics below).

We have most of this form under /story_ideas/new, and now need to add the multiselect checkboxes to that form.

Let's add story_populations as a json field to Story and StoryIdea

Both models will need to:
has_many :categorizable_items, dependent: :destroy, as: :categorizable
has_many :categories, through: :categorizable_items

And then the accepts_nested_attributes so these can pass via strong params