Update: Refactored and added bucket action tests

coscine/issues#2424

src/IPConnectivityChecker/Enums/EcsLocations.cs

+using Newtonsoft.Json.Converters;
+using System.ComponentModel;
+using System.Runtime.Serialization;
+
+namespace IPConnectivityChecker.Enums;
+
+[TypeConverter(typeof(StringEnumConverter))]
+public enum EcsLocations
+{
+    /// <summary>
+    /// Test ECS of RWTH Aachen University
+    /// </summary>
+    [EnumMember(Value = "rwth")]
+    RWTH,
+    /// <summary>
+    /// Test ECS of North Rhine-Westphalia
+    /// </summary>
+    [EnumMember(Value = "nrw")]
+    NRW,
+    /// <summary>
+    /// Test ECS of TU Dortmund
+    /// </summary>
+    [EnumMember(Value = "tudo")]
+    TUDO,
+    /// <summary>
+    /// Test ECS of University of Duisburg-Essen
+    /// </summary>
+    [EnumMember(Value = "ude")]
+    UDE
+}