ENH: adjust fileName methods for similarity to std::filesystem::path

- stem(), replace_name(), replace_ext(), remove_ext() etc

- string::contains() method - similar to C++23 method

  Eg,
      if (keyword.contains('/')) ...
  vs
      if (keyword.find('/') != std::string::npos) ...

applications/utilities/surface/surfaceBooleanFeatures/surfaceBooleanFeatures.C

@@ -1718,9 +1718,9 @@ int main(int argc, char *argv[])
 
     const fileName sFeatFileName
     (
-        fileName(surf1Name).nameLessExt()
+        fileName::stem(surf1Name)
       + "_"
-      + fileName(surf2Name).nameLessExt()
+      + fileName::stem(surf2Name)
       + "_"
       + action
     );