STYLE: check iterator validity with good() instead of found()

- aligns better with other container checks

src/functionObjects/field/binField/binModels/binModel/binModelNew.C

@@ -41,7 +41,7 @@ Foam::autoPtr<Foam::binModel> Foam::binModel::New
 
     auto cstrIter = dictionaryConstructorTablePtr_->cfind(modelType);
 
-    if (!cstrIter.found())
+    if (!cstrIter.good())
     {
         FatalIOErrorInLookup
         (

src/functionObjects/field/externalCoupled/externalCoupled.C

@@ -607,7 +607,7 @@ bool Foam::functionObjects::externalCoupled::read(const dictionary& dict)
             const wordList writeFields(groupDict.get<wordList>("writeFields"));
 
             auto fnd = regionToGroups_.find(regionGroupNames_.last());
-            if (fnd.found())
+            if (fnd.good())
             {
                 fnd().append(nGroups);
             }

src/functionObjects/utilities/runTimeControl/runTimeControl.C

@@ -211,7 +211,7 @@ bool Foam::functionObjects::runTimeControls::runTimeControl::execute()
 
             auto conditionIter = groupMap_.cfind(groupi);
 
-            if (!conditionIter.found())
+            if (!conditionIter.good())
             {
                 FatalErrorInFunction
                     << "group " << groupi << " not found in map"