fix: `AttributeKey` code generation

Usage of AttributeKey in endpoints code generation fails with Not enough information to infer type variable T.

Example usage:

return Endpoint(
    Url.parse("${url?.scheme}://${url?.authority}/${uriEncodedBucket}${url?.path}"),
    attributes = attributesOf {
        AttributeKey("backend") to "FOOBAR" // Not enough information to infer type variable T
        SigningContextAttributeKey to listOf(
            sigV4(
                serviceName = "s3",
                disableDoubleUriEncode = true,
                signingRegion = "${params.region}",
            ),
        )
    },
)

The fix is to provide the type for AttributeKey<T>. New codegen will look like:

AttributeKey.create("backend", "FOOBAR") to "FOOBAR"

This is done to avoid type-parsing at codegen and just let the Kotlin compiler work it out.

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smithy-lang / smithy-kotlin

fix: `AttributeKey` code generation #1001

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