Protocol tests and floating point comparisons

[david-perez]

Server protocol tests are using the PartialEq implementation on floating point types because they assert_eq on the containing operation input shape.

Client protocol tests, on the other hand, always iterate over the shape's members and use aws_smithy_protocol_test::FloatEquals.

This trait differs in float’s default PartialEq implementation by considering all NaN values to be equal.

I stumbled upon this earlier in smithy-lang/smithy#1040 (comment). I think this fix is fair.

However, I don't see this trait being used recursively in the client tests i.e. the shape containing floating point types could be nested.

https://github.com/awslabs/smithy-rs/blob/4b8381b22c8d4b8eebea60bdc6a666bb75dece57/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGenerator.kt#L326-L335