fix #16412 elixir outer enum bug

[montague]

This fixes a bug where an outer enum isn't properly deserialized in the generated Elixir client. See this issue. #16412

I added one test to exercise the failure case, which I got from this PR #19435 as I was searching to see if anyone else had been having the same problem I ran into.

@tobbbles I grabbed your failing test from #19435 and included it here to speed things up. Thank you for your prior work on this. It pointed me in the right direction.

Real team effort here!

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Relates to #16412

This PR fixes a bug in the Elixir generator @mrmstn

[mrmstn]

Hi @montague,
Thanks for the PR and the fix of the issue. LGTM and pipline is green as well

Given the error description of #16412 (comment) I think this won't break anything and should fix the enum issue.

I'll check if I can merge this in the upcomimng days, so this will be included in the next release

[tobbbles]

Amazing work, thank you! I'm going to test generating the ory SDKs from this commit, and validate that end use cases work.

[montague]

I realized I may have only fixed a part of the issue. Keep me updated on your use case @tobbbles.