Entities with positional arguments, whose arguments are keyword lists cannot be set.

[jimsynz]

Describe the bug

Given an entity which takes a keyword list as it's first argument:

%Spark.Dsl.Entity{
  name: :example,
  args: [:my_options],
  schema: [
     my_options: [
      type: :non_empty_keyword_list,
      required: true
     ]
  ]
}

Attempting to use it in a DSL like so:

example marty: :mcfly

Will raise an error about there being no option named :marty in the entity's schema.

Expected behavior
A clear and concise description of what you expected to happen.

It should return the built entity with [{:marty, :mcfly}] in the :my_options field.

Additional context
Discussed in Slack in the context of adding a load entity to Ash.Reactor action steps.