Fix: Remove duplicate enum values in HttpStatusCode dropdown for WriteHttpResponse

[zengande]

When generating the dropdown list for the status input in the WriteHttpResponse activity, duplicate enum values were included due to Enum.GetValues() returning multiple names with the same underlying numeric value from System.Net.HttpStatusCode.

This fix filters the list to include only distinct values, grouped by their underlying integer representation.

Related issue: #6845

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This change is 

[Copilot]

Pull Request Overview

This PR fixes a bug where the WriteHttpResponse activity's status code dropdown displayed duplicate entries. The issue arose because System.Net.HttpStatusCode contains multiple enum names with the same underlying integer values (e.g., HttpStatusCode.Ambiguous and HttpStatusCode.MultipleChoices both equal 300).

Key Changes:

• Modified StaticDropDownOptionsProvider to deduplicate enum values by grouping on their integer representation and selecting the first name for each unique value.

[Copilot]

The deduplication logic uses Convert.ToInt32 which will fail for enums with underlying types other than int (e.g., long, byte, short). While HttpStatusCode uses int, this is a generic enum handler. Consider using Enum.GetUnderlyingType() to safely convert values regardless of the underlying type, or use GroupBy(x => x) with a custom comparer to avoid type-specific conversion altogether.

Suggested change

	var enumValues = Enum.GetValues(wrappedPropertyType)
	.Cast<Enum>()
	.GroupBy(Convert.ToInt32)
	var underlyingType = Enum.GetUnderlyingType(wrappedPropertyType);
	var enumValues = Enum.GetValues(wrappedPropertyType)
	.Cast<Enum>()
	.GroupBy(x => Convert.ChangeType(x, underlyingType))