Added provider for logged in Windows users

lib/provider/users/Get-IcingaLoggedOnUsers.psm1

@@ -0,0 +1,43 @@
+function Get-IcingaLoggedOnUsers()
+{
+    param(
+        [array]$UserFilter = @()
+    );
+
+    [hashtable]$UserList = @{};
+    [int]$UserCount      = 0;
+    $UserList.Add('users', @{ });
+
+    $Users = Get-CIMInstance Win32_LoggedOnUser | Select-Object Antecedent, Dependent;
+
+    foreach ($user in $Users) {
+        [string]$username = $user.Antecedent.Name;
+
+        if ($UserFilter.Count -ne 0) {
+            if (-Not $UserFilter.Contains($username)) {
+                continue;
+            }
+        }
+
+        $UserCount += 1;
+
+        if ($UserList.users.ContainsKey($username) -eq $FALSE) {
+            $UserList.users.Add(
+                $username,
+                @{
+                    'domains' = @($user.Antecedent.Domain);
+                    'logonid' = @($user.Dependent.LogonId);
+                    'count'   = 1;
+                }
+            );
+        } else {
+            $UserList.users[$username].domains += $user.Antecedent.Domain;
+            $UserList.users[$username].logonid += $user.Dependent.LogonId;
+            $UserList.users[$username].count   += 1;
+        }
+    }
+
+    $UserList.Add('count', $UserCount);
+
+    return $UserList;
+}