Returned map in steps is inconsistent with the result

[darwin67]

Overview

When returning a map in a step like this.

result = step.run(ctx, "step", fn ->
  %{foo: "bar"}
end)

The result is set to %{ "foo" => "bar" } instead of %{foo: "bar"} which is what you'd expect from the code.

This will raise an error if you try to pattern match against the returned value when doing

%{foo: _} = step.run(ctx, "step", fn ->
  %{foo: "bar"}
end)

[darwin67]

Provided an options and make it step.run/3 so user can specify the map structure they expect.

Also provide a configurable library default option, with the steps being the final override.

Discussion:
https://elixirforum.com/t/pattern-match-on-map-keys-that-can-be-atoms-or-strings/63760/7