fix: Protocol tests & implementation for FP numbers in query & headers are wrong

[jbelkins]

Description of changes

The existing request protocol tests replace the values Infinity, -Infinity, and NaN (the Smithy convention for these values) with the values inf, -inf, and nan (which are how Swift prints them). The Swift SDK implementation passes protocol tests because both the tests and the implementation are wrong in the same way.

To address:

• The code which replaces the Smithy values for special FP values is removed from the test verification code; this causes 24 protocol tests to fail since the tests now expect the correct values but the implementation isn't compliant.
• The implementation for headers, query items, and query item lists is fixed so it sends the correct representation for special floating point values. This corrects the protocol tests that started to fail above.
• Tests are added for query item lists since that case isn't covered in protocol tests.

Also: a little cleanup of Kotlin code warnings.

Scope

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.