Refactor user group name handling in TfsUserMappingTool

Replaced hardcoded "Project Collection Valid Users" string
in `TfsUserMappingTool.cs` with a configurable property
`Options.ProjectCollectionValidUsersGroupName`. Added
this property to `TfsUserMappingToolOptions.cs` to allow
customization of the group name, with a default value
of "Project Collection Valid Users".

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsUserMappingTool.cs

@@ -121,7 +121,7 @@ private Dictionary<string, string> GetMappingFileData()
 
         private List<IdentityItemData> GetUsersListFromServer(IGroupSecurityService gss)
         {
-            Identity allIdentities = gss.ReadIdentity(SearchFactor.AccountName, "Project Collection Valid Users", QueryMembership.Expanded);
+            Identity allIdentities = gss.ReadIdentity(SearchFactor.AccountName, Options.ProjectCollectionValidUsersGroupName, QueryMembership.Expanded);
             Log.LogInformation("TfsUserMappingTool::GetUsersListFromServer Found {count} identities (users and groups) in server.", allIdentities.Members.Length);
 
             List<IdentityItemData> foundUsers = new List<IdentityItemData>();

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsUserMappingToolOptions.cs

@@ -31,6 +31,12 @@ public class TfsUserMappingToolOptions : ToolOptions, ITfsUserMappingToolOptions
         /// </summary>
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
         public bool SkipValidateAllUsersExistOrAreMapped { get; set; } = false;
+
+        /// <summary>
+        /// This is the regionalized "Project Collection Valid Users" group name. Default is "Project Collection Valid Users".
+        /// </summary>
+        public string ProjectCollectionValidUsersGroupName { get; set; } = "Project Collection Valid Users";
+
     }
 
     public interface ITfsUserMappingToolOptions