Added MultiSelect input control for provider settings

Signed-off-by: Robin Dadswell <robin@dadswell.email>

src/Readarr.Http/ClientSchema/SchemaBuilder.cs

@@ -142,10 +142,34 @@ namespace Readarr.Http.ClientSchema
 
         private static List<SelectOption> GetSelectOptions(Type selectOptions)
         {
-            var options = from Enum e in Enum.GetValues(selectOptions)
-                          select new SelectOption { Value = Convert.ToInt32(e), Name = e.ToString() };
+            var options = selectOptions.GetFields().Where(v => v.IsStatic).Select(v =>
+            {
+                var name = v.Name.Replace('_', ' ');
+                var value = Convert.ToInt32(v.GetRawConstantValue());
+                var attrib = v.GetCustomAttribute<FieldOptionAttribute>();
+                if (attrib != null)
+                {
+                    return new SelectOption
+                    {
+                        Value = value,
+                        Name = attrib.Label ?? name,
+                        Order = attrib.Order,
+                        Hint = attrib.Hint ?? $"({value})"
+                    };
+                }
+                else
+                {
+                    return new SelectOption
+                    {
+                        Value = value,
+                        Name = name,
+                        Order = value,
+                        Hint = $"({value})"
+                    };
+                }
+            });
 
-            return options.OrderBy(o => o.Value).ToList();
+            return options.OrderBy(o => o.Order).ToList();
         }
 
         private static Func<object, object> GetValueConverter(Type propertyType)