ENH: use hasEnv() instead of env() for naming symmetry with getEnv, setEnv

- less confusing than the env() name, which could look like a
  setter/getter instead of a test

applications/test/foamEnv/Make/files

@@ -0,0 +1,3 @@
+Test-foamEnv.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-foamEnv

applications/test/foamEnv/Make/options

@@ -0,0 +1,2 @@
+/* EXE_INC = */
+/* EXE_LIBS = */

applications/test/foamEnv/Test-foamEnv.C

@@ -0,0 +1,79 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2020 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-etcFiles
+
+Description
+    Test etcFiles functionality.
+    Similar to foamEtcFile script, but automatically prunes nonexistent
+    directories from the list.
+
+\*---------------------------------------------------------------------------*/
+
+#include "argList.H"
+#include "OSspecific.H"
+
+using namespace Foam;
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+// Main program:
+
+int main(int argc, char *argv[])
+{
+    argList::noBanner();
+    argList::noParallel();
+    argList::noFunctionObjects();
+    argList::removeOption("case");
+
+    argList::addArgument("env...");
+
+    argList::addNote
+    (
+        "Simple test/report OpenFOAM environment"
+    );
+
+    argList args(argc, argv, false, true);
+
+    for (int argi = 1; argi < args.size(); ++argi)
+    {
+        const std::string envName(args[argi]);
+
+        if (hasEnv(envName))
+        {
+            Info<<"Have env " << envName.c_str() << "=" << getEnv(envName)
+                << nl;
+        }
+        else
+        {
+            Info<<"No env " << envName.c_str()<< nl;
+        }
+    }
+
+    return 0;
+}
+
+
+// ************************************************************************* //