ENH: globalIndex and CompactListList improvements

- provide a globalIndex::calcOffsets() taking an indirect list, which
  enables convenient offsets calculation from a variety of inputs.

- new CompactListList unpack variant: copy_unpack()
  The copy_unpack() works somewhat like std::copy() in that it writes
  the generated sublists to iterator positions, which makes this
  type of code possible:

      CompactListList<label> compact = ...;
      DynamicList<face> extracted;

      compact.copy_unpack<face>
      (
          std::back_inserter(extracted),
          labelRange(4, 10)
      );

  -and-

      const label nOldFaces = allFaces.size();
      allFaces.resize(allFaces + nNewFaces);

      auto iter = allFaces.begin(nOldFaces);

      iter = compact.copy_unpack<face>(iter, /* selection 1 */);
      ...
      iter = compact.copy_unpack<face>(iter, /* selection 2 */);

ENH: globalIndex resize()

- can be used to shrink or grow the offsets table.
  Any extension of the offsets table corresponds to 'slots'
  with 0 local size.

applications/test/globalIndex2/Test-globalIndex2.cxx

@@ -0,0 +1,95 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Application
+    Test-globalIndex2
+
+Description
+    More functional tests for the globalIndex class.
+
+\*---------------------------------------------------------------------------*/
+
+#include "globalIndex.H"
+#include "argList.H"
+#include "Time.H"
+#include "IOstreams.H"
+#include "Random.H"
+#include "IndirectList.H"
+#include "SliceList.H"
+
+using namespace Foam;
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+//  Main program:
+
+int main(int argc, char *argv[])
+{
+    Random rnd(123456);
+
+    // #include "setRootCase.H"
+    // #include "createTime.H"
+
+    Info<< nl
+        << "simple globalIndex tests" << nl << nl;
+
+    Info<< "Construct from indirect list(s)" << nl;
+    {
+        // Some sizes
+        labelList rawSizes(25);
+        forAll(rawSizes, i)
+        {
+            rawSizes[i] = rnd.position<label>(0, 100);
+        }
+
+        Info<< nl
+            << "plain sizes: "
+            << flatOutput(rawSizes) << nl
+            << "    offsets: "
+            << flatOutput(globalIndex::calcOffsets(rawSizes))
+            << nl;
+
+
+        sliceRange slice(0, 5, 5);
+        Info<< nl
+            << "range min/max " << slice.min() << '/' << slice.max() << nl;
+
+        SliceList<label> sliceSizes(rawSizes, slice);
+
+        Info<< nl
+            << "indirect addr: " << sliceSizes.addressing() << nl
+            << "indirect sizes: "
+            << flatOutput(sliceSizes) << nl
+            << "       offsets: "
+            << flatOutput(globalIndex::calcOffsets(sliceSizes))
+            << nl;
+    }
+
+    Info<< "\nEnd\n" << endl;
+    return 0;
+}
+
+
+// ************************************************************************* //