fix: HTTPAPIKeyAuthTrait initialization

[nated0g]

Issue #, if available:

Description of changes:

The initializer of the HTTPAPIKeyAuthTrait as currently implemented is incorrect. As it is currently written, initialization will always fail. The httpApiKeyAuth trait in the generated schema code ends up looking like this:

Trait.new(
    id=ShapeID("smithy.api#httpApiKeyAuth"),
    value=MappingProxyType({"name": "Authorization", "in": "header"}),
),

When building:

  File "/app/smithy/build/conversations/python-client-codegen/src/conversations/_private/schemas.py", line 1036, in <module>
    Trait.new(
    ~~~~~~~~~^
        id=ShapeID("smithy.api#httpApiKeyAuth"),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        value=MappingProxyType({"name": "Authorization", "in": "header"}),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ),
    ^
  File "/app/.venv/lib/python3.13/site-packages/smithy_core/traits.py", line 91, in new
    return cls(value)
  File "/app/.venv/lib/python3.13/site-packages/smithy_core/traits.py", line 338, in __init__
    object.__setattr__(self, "location", APIKeyLocation(value))
                                         ~~~~~~~~~~~~~~^^^^^^^
  File "/usr/local/lib/python3.13/enum.py", line 726, in __call__
    return cls.__new__(cls, value)
           ~~~~~~~~~~~^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/enum.py", line 1203, in __new__
    raise ve_exc
ValueError: mappingproxy({'name': 'Authorization', 'in': 'header'}) is not a valid APIKeyLocation

The current implementation tries to construct an APIKeyLocation from this entire object, instead of from the required in property (https://smithy.io/2.0/spec/authentication-traits.html#httpapikeyauth-trait), as it should.

This change constructs the APIKeyLocation correctly from the in property

---

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[jonathan343]

Hey @nated0g,

Thanks for opening this pull request!
I think this looks good but the type checker is probably gonna complain since this is being added before the assert isinstance(self.document_value, Mapping) line.

I'll run our CI so you can see what I'm taking about.
All you'll need to do is move these lines below the one I mentioned above.

[nated0g]

Hey @nated0g,

Thanks for opening this pull request! I think this looks good but the type checker is probably gonna complain since this is being added before the assert isinstance(self.document_value, Mapping) line.

I'll run our CI so you can see what I'm taking about. All you'll need to do is move these lines below the one I mentioned above.

Good call, done.

[jonathan343]

LGTM!

[jonathan343]

Thanks again @nated0g!
I'll add a bugfix changelog entry for this in #552