Added API endpoints classes for all CFCore web API endpoints.

A few have not been implemented.

CFCoreAPI/Endpoints/Responses/StringResponse.cs

@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+
+namespace CFCoreAPI.Endpoints.Files.Responses
+{
+    public struct StringResponse
+    {
+        [JsonConstructor]
+        public StringResponse(
+            string data
+        )
+        {
+            this.Data = data;
+        }
+
+        public string Data { get; }
+    }
+}