functionObjectList: Moved the functions entry from controlDict into a functions file

for consistency with fvModels and fvConstraints, to simplify code and case
maintenance and to avoid the potentially complex functions entries being
unnecessarily parsed by utilities for which functionObject evaluation is
disabled.

The functions entry in controlDict is still read if the functions file is not
present for backward-compatibility, but it is advisable to migrate cases to use
the new functions file.

applications/utilities/postProcessing/foamPostProcess/foamPostProcess.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -279,19 +279,10 @@ int main(int argc, char *argv[])
         }
     }
 
-    // Externally stored dictionary for functionObjectList
-    // if not constructed from runTime
-    dictionary functionsControlDict("controlDict");
-
     // Construct functionObjectList
     autoPtr<functionObjectList> functionsPtr
     (
-        functionObjectList::New
-        (
-            args,
-            runTime,
-            functionsControlDict
-        )
+        functionObjectList::New(args, runTime)
     );
 
     forAll(timeDirs, timei)
@@ -303,12 +294,7 @@ int main(int argc, char *argv[])
         if (mesh.readUpdate() != fvMesh::UNCHANGED)
         {
             // Update functionObjectList if mesh changes
-            functionsPtr = functionObjectList::New
-            (
-                args,
-                runTime,
-                functionsControlDict
-            );
+            functionsPtr = functionObjectList::New(args, runTime);
         }
 
         FatalIOError.throwExceptions();