feat: Outstream operator for TrackStatePropMask (#1165)

I've found this very helpful for some types of debugging.

Core/include/Acts/EventData/TrackStatePropMask.hpp

@@ -11,6 +11,7 @@
 #include "Acts/Utilities/EnumBitwiseOperators.hpp"
 
 #include <limits>
+#include <ostream>
 #include <type_traits>
 
 namespace Acts {
@@ -38,4 +39,6 @@ enum struct TrackStatePropMask : uint8_t {
 
 ACTS_DEFINE_ENUM_BITWISE_OPERATORS(TrackStatePropMask)
 
+std::ostream& operator<<(std::ostream& os, TrackStatePropMask mask);
+
 }  // namespace Acts

Core/src/EventData/CMakeLists.txt

@@ -6,4 +6,5 @@ target_sources(
     TrackParameters.cpp
     TransformationBoundToFree.cpp
     TransformationFreeToBound.cpp
+    TrackStatePropMask.cpp
 )

Core/src/EventData/TrackStatePropMask.cpp

@@ -0,0 +1,41 @@
+// This file is part of the Acts project.
+//
+// Copyright (C) 2022 CERN for the benefit of the Acts project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "Acts/EventData/TrackStatePropMask.hpp"
+
+#include "Acts/Utilities/Helpers.hpp"
+
+#include <ostream>
+
+namespace Acts {
+
+std::ostream& operator<<(std::ostream& os, TrackStatePropMask mask) {
+  using PM = TrackStatePropMask;
+  os << "TrackStatePropMask(";
+  if (mask == PM::None) {
+    os << "None";
+  } else {
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Predicted) ? "x" : " ")
+       << "] predicted";
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Filtered) ? "x" : " ")
+       << "] filtered";
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Smoothed) ? "x" : " ")
+       << "] smoothed";
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Jacobian) ? "x" : " ")
+       << "] jacobian";
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Uncalibrated) ? "x" : " ")
+       << "] uncalibrated";
+    os << "\n  [" << (ACTS_CHECK_BIT(mask, PM::Calibrated) ? "x" : " ")
+       << "] calibrated";
+    os << "\n";
+  }
+  os << ")";
+  return os;
+}
+
+}  // namespace Acts