[Feature] RespondWithModal() which accepts an IModal instance as template (#2564)

* introduce overload for responding to an interaction with an instatiated IModal obj

* add inline docs to ModalInfo.PropertyInfo

* Apply suggestions from code review

Co-authored-by: Casmir <68127614+csmir@users.noreply.github.com>

---------

Co-authored-by: Casmir <68127614+csmir@users.noreply.github.com>

src/Discord.Net.Interactions/Utilities/ReflectionUtils.cs

@@ -10,7 +10,6 @@ namespace Discord.Interactions
     internal static class ReflectionUtils<T>
     {
         private static readonly TypeInfo ObjectTypeInfo = typeof(object).GetTypeInfo();
-
         internal static T CreateObject (TypeInfo typeInfo, InteractionService commandService, IServiceProvider services = null) =>
             CreateBuilder(typeInfo, commandService)(services);
 
@@ -166,6 +165,21 @@ namespace Discord.Interactions
             return Expression.Lambda<Action<T, object>>(assign, instanceParam, valueParam).Compile();
         }
 
+        internal static Func<T, object> CreateLambdaPropertyGetter(PropertyInfo propertyInfo)
+        {
+            var instanceParam = Expression.Parameter(typeof(T), "instance");
+            var prop = Expression.Property(instanceParam, propertyInfo);
+            return Expression.Lambda<Func<T, object>>(prop, instanceParam).Compile();
+        }
+
+        internal static Func<T, object> CreateLambdaPropertyGetter(Type type, PropertyInfo propertyInfo)
+        {
+            var instanceParam = Expression.Parameter(typeof(T), "instance");
+            var instanceAccess = Expression.Convert(instanceParam, type);
+            var prop = Expression.Property(instanceAccess, propertyInfo);
+            return Expression.Lambda<Func<T, object>>(prop, instanceParam).Compile();
+        }
+
         internal static Func<object[], object[], T> CreateLambdaMemberInit(TypeInfo typeInfo, ConstructorInfo constructor, Predicate<PropertyInfo> propertySelect = null)
         {
             propertySelect ??= x => true;