Reduce allocations on list deserialization (#310)

* Do not capture context on async awaits

* Do not capture context on async awaits (2)

* Improve list allocation when deserializing lists from messages

* Fixed List implementation with initial capacity

* Fixed list implementation for NETMF

netmf/NetMF/List.cs

@@ -24,5 +24,20 @@ namespace Amqp.Types
     /// </summary>
     public class List : ArrayList
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="List"/> class.
+        /// </summary>
+        public List()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="List"/> class.
+        /// </summary>
+        /// <param name="capacity">The number of elements that the new list can initially store.</param>
+        public List(int capacity) : base()
+        {
+            // NOTE: NETMF ArrayList does not have a constructor that takes an int parameter, so we cannot set initial capacity in this case
+        }
     }
 }

src/Net/List.cs

@@ -24,5 +24,20 @@ namespace Amqp.Types
     /// </summary>
     public class List : List<object>
     {
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="List"/> class.
+        /// </summary>
+        public List()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="List"/> class.
+        /// </summary>
+        /// <param name="capacity">The number of elements that the new list can initially store.</param>
+        public List(int capacity) : base(capacity)
+        {
+        }
     }
 }

src/Types/Encoder.cs

@@ -1346,7 +1346,7 @@ public static List ReadList(ByteBuffer buffer, byte formatCode)
                 throw InvalidFormatCodeException(formatCode, buffer.Offset);
             }
 
-            List value = new List();
+            List value = new List(count);
             for (int i = 0; i < count; ++i)
             {
                 value.Add(ReadObject(buffer));