Fix check for form parameters that don't need complex binding in RDG

[captainsafia]

Closes #55840.

aspnetcore/src/Http/Http.Extensions/gen/StaticRouteHandlerModel/EndpointParameter.cs

Lines 110 to 119 in 83573c7

	// Complex form binding is only supported in RDF because it uses shared source with Blazor that requires dynamic analysis
	// and codegen. Emit a diagnostic when these are encountered to avoid producing buggy code.
	else if (!(SymbolEqualityComparer.Default.Equals(Type, wellKnownTypes.Get(WellKnownType.Microsoft_Extensions_Primitives_StringValues))
	|| Type.SpecialType == SpecialType.System_String
	|| TryGetParsability(Type, wellKnownTypes, out var _)
	|| (IsArray && TryGetParsability(ElementType, wellKnownTypes, out var _))))
	{
	var location = endpoint.Operation.Syntax.GetLocation();
	endpoint.Diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.UnableToResolveParameterDescriptor, location, symbol.Name));
	}

The condition added in the code referenced above needs an additional (IsArray && ElementType.SpecialType == SpecialType.System_String) check since we don't don't generate a parsability method for string types out of TryGetParsability.

[captainsafia]

/azp run

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