Fixed System.Text.Json array converter deserialization when skipping indexes, added NumberStringConverter

CryptoExchange.Net/Converters/SystemTextJson/NumberStringConverter.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Globalization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace CryptoExchange.Net.Converters.SystemTextJson
+{
+    /// <summary>
+    /// Read string or number as string
+    /// </summary>
+    public class NumberStringConverter : JsonConverter<string?>
+    {
+        /// <inheritdoc />
+        public override string? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            if (reader.TokenType == JsonTokenType.Null)
+                return null;
+
+            if (reader.TokenType == JsonTokenType.Number)
+                return reader.GetInt64().ToString();
+
+            return reader.GetString();
+        }
+
+        /// <inheritdoc />
+        public override void Write(Utf8JsonWriter writer, string? value, JsonSerializerOptions options)
+        {
+            writer.WriteStringValue(value);
+        }
+    }
+}