Support binding from types defined with an `AsParameters` attribute

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Support binding parameters that are encapsulated in a type marked with an AsParameters type.

• Supports existing parameter types (FromX, implicit route or query, implicit JSON body or service, form)
• Support parameter types that need ParameterInfo (BindAsync and IEndpointParameterMetadataProvider)
• Supports nullability in properties and constructor parameter
• Emits diagnostics for malformed AsParameters type