GreenField: Payment Requests CRUD (#1430)

* GreenField: Payment Requests CRUD

* fixes

* fix swagger

* fix swag

* rebase fixes

* Add new permissions for payment requests

* Adapt PR to archive

* fix tst

* add to contains policxy

* make decimals returned as string due to avoid shitty language parsing issues

* do not register decimal json converter as global

* fix cultureinfo for json covnerter

* pr changes

* add json convertet test

* fix json test

* fix rebase

BTCPayServer.Client/JsonConverters/DecimalStringJsonConverter.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Globalization;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace BTCPayServer.JsonConverters
+{
+    public class DecimalStringJsonConverter : JsonConverter
+    {
+        public override bool CanConvert(Type objectType)
+        {
+            return (objectType == typeof(decimal) || objectType == typeof(decimal?));
+        }
+
+        public override object ReadJson(JsonReader reader, Type objectType, object existingValue,
+            JsonSerializer serializer)
+        {
+            JToken token = JToken.Load(reader);
+            switch (token.Type)
+            {
+                case JTokenType.Float:
+                case JTokenType.Integer:
+                case JTokenType.String:
+                    return decimal.Parse(token.ToString(), CultureInfo.InvariantCulture);
+                case JTokenType.Null when objectType == typeof(decimal?):
+                    return null;
+                default:
+                    throw new JsonSerializationException("Unexpected token type: " +
+                                                         token.Type);
+            }
+        }
+
+        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+        {
+            if (value != null)
+                writer.WriteValue(((decimal)value).ToString(CultureInfo.InvariantCulture));
+        }
+    }
+}