searchableSurface: Renamed geometry directory triSurface -> geometry

Originally the only supported geometry specification were triangulated surfaces,
hence the name of the directory: constant/triSurface, however now that other
surface specifications are supported and provided it is much more logical that
the directory is named accordingly: constant/geometry.  All tutorial and
template cases have been updated.

Note that backward compatibility is provided such that if the constant/geometry
directory does not exist but constant/triSurface does then the geometry files
are read from there.

applications/utilities/mesh/manipulation/createBaffles/createBaffles.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -49,7 +49,7 @@ Description
 #include "pointFields.H"
 #include "fvMeshMapper.H"
 #include "faceSelection.H"
-
+#include "searchableSurface.H"
 #include "fvMeshTools.H"
 
 using namespace Foam;
@@ -446,7 +446,6 @@ int main(int argc, char *argv[])
     runTime.functionObjects().off();
     #include "createNamedMesh.H"
 
-
     const bool overwrite = args.optionFound("overwrite");
 
     const word oldInstance = mesh.pointsInstance();