Update ITlsHandshakeFeature.HostName API + misc. improvements in HttpSys calls

[karimsalem1]

Update ITlsHandshakeFeature.HostName API + misc. improvements in HttpSys calls

Summary of the changes (Less than 80 chars)

Updating the ITlsHandshakeFeature.HostName API as discussed in #34525 and miscellaneous improvements in HttpQueryRequestProperty calls + cleanup

Description

The PR does the following changes:

• Updates the ITlsHandshakeFeature.HostName property to be non-nullable and updates all references accordingly.
• Changes HTTPAPI HttpQueryRequestProperty method definition to have an invoker similar to HttpSetRequestPropertyInvoker. This API might not be present on older OS's so it'll be guarded by an Invoker and null check to ensure backwards compatibility.
• Updates the HttpQueryRequestProperty parameters qualifierSize, outputSize and bytesReturned to be uint instead of ulong. Based on the HttpSys API (shown below), these are ULONG which are 32 bits in Windows. Also updated the propertyInfoSetSize parameter in HttpDelegateRequestEx for the same reason.

HttpQueryRequestProperty(
    _In_ HANDLE RequestQueueHandle,
    _In_ HTTP_OPAQUE_ID Id,
    _In_ HTTP_REQUEST_PROPERTY PropertyId,
    _In_reads_bytes_opt_(QualifierSize) PVOID Qualifier,
    _In_ ULONG QualifierSize,
    _Out_writes_bytes_to_opt_(OutputBufferSize, *BytesReturned) PVOID Output,
    _In_ ULONG OutputBufferSize,
    _Out_opt_ PULONG BytesReturned,
    _In_ LPOVERLAPPED Overlapped
    );

• Cleans up extra namespaces introduced in previous PR and changes HTTP_REQUEST_PROPERTY_SNI_HOST_MAX_LENGTH to private

Link to previous PR: #48572

[ghost]

Thanks for your PR, @karimsalem1. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[karimsalem1]

/azp run

[azure-pipelines]

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