ENH: PatchParticleHistogram: add a new cloud FO

Summary

Computes a histogram for the distribution of particle diameters and corresponding number of particles hitting on a given list of patches.

A minimal example by using constant/reactingCloud1Properties.cloudFunctions:

patchParticleHistogram1
{
    // Mandatory entries (unmodifiable)
    type             patchParticleHistogram;
    patches          (<patch1> <patch2> ... <patchN>);
    nBins            10;
    min              0.1;
    max              10.0;
    maxStoredParcels 20;
}

Risks

No change to user inputs / no risk to regression.

PS: approval/feedback please @mark @Sergio @Mattijs @Prashant

src/lagrangian/intermediate/parcels/include/makeParcelCloudFunctionObjects.H

@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2018 OpenFOAM Foundation
+    Copyright (C) 2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -37,6 +38,7 @@ License
 #include "ParticleTrap.H"
 #include "PatchCollisionDensity.H"
 #include "PatchPostProcessing.H"
+#include "PatchParticleHistogram.H"
 #include "RemoveParcels.H"
 #include "VoidFraction.H"
 
@@ -53,6 +55,7 @@ License
     makeCloudFunctionObjectType(ParticleTrap, CloudType);                      \
     makeCloudFunctionObjectType(PatchCollisionDensity, CloudType);             \
     makeCloudFunctionObjectType(PatchPostProcessing, CloudType);               \
+    makeCloudFunctionObjectType(PatchParticleHistogram, CloudType);            \
     makeCloudFunctionObjectType(RemoveParcels, CloudType);                     \
     makeCloudFunctionObjectType(VoidFraction, CloudType);