ENH: consolidate 'formatOptions' handling for coordSetWriter/surfaceWriter

- replaced ad hoc handling of formatOptions with coordSetWriter and
  surfaceWriter helpers.

  Accompanying this change, it is now possible to specify "default"
  settings to be inherited, format-specific settings and have a
  similar layering with surface-specific overrides.

- snappyHexMesh now conforms to setFormats

  Eg,

      formatOptions
      {
          default
          {
              verbose     true;
              format      binary;
          }
          vtk
          {
              precision   10;
          }
     }

     surfaces
     {
         surf1
         {
             ...

             formatOptions
             {
                 ensight
                 {
                     scale   1000;
                 }
             }
         }
     }

src/functionObjects/field/Curle/Curle.C

@@ -161,11 +161,12 @@ bool Foam::functionObjects::Curle::read(const dictionary& dict)
                     << abort(FatalIOError);
             }
 
-            const word surfaceType(dict.get<word>("surfaceType"));
+            const word writerType = dict.get<word>("surfaceType");
+
             surfaceWriterPtr_ = surfaceWriter::New
             (
-                surfaceType,
-                dict.subOrEmptyDict("formatOptions").subOrEmptyDict(surfaceType)
+                writerType,
+                surfaceWriter::formatOptions(dict, writerType)
             );
 
             // Use outputDir/TIME/surface-name

src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C

@@ -1138,14 +1138,14 @@ bool Foam::functionObjects::fieldValues::surfaceFieldValue::read
 
     if (writeFields_)
     {
-        const word formatName(dict.get<word>("surfaceFormat"));
+        const word writerType = dict.get<word>("surfaceFormat");
 
         surfaceWriterPtr_.reset
         (
             surfaceWriter::New
             (
-                formatName,
-                dict.subOrEmptyDict("formatOptions").subOrEmptyDict(formatName)
+                writerType,
+                surfaceWriter::formatOptions(dict, writerType)
             )
         );
 
@@ -1159,7 +1159,7 @@ bool Foam::functionObjects::fieldValues::surfaceFieldValue::read
 
         if (surfaceWriterPtr_->enabled())
         {
-            Info<< "    surfaceFormat = " << formatName << nl;
+            Info<< "    surfaceFormat = " << writerType << nl;
         }
         else
         {

src/functionObjects/forces/propellerInfo/propellerInfo.C

@@ -355,16 +355,20 @@ void Foam::functionObjects::propellerInfo::setSampleDiskSurface
         points_
     );
 
-    // Surface writer
-    word surfWriterType;
-    if (sampleDiskDict.readIfPresent("surfaceWriter", surfWriterType))
-    {
-        const auto writeOptions = sampleDiskDict.subOrEmptyDict("writeOptions");
+    // Surface writer (keywords: surfaceWriter, writeOptions)
 
+    word writerType;
+    if (sampleDiskDict.readIfPresent("surfaceWriter", writerType))
+    {
         surfaceWriterPtr_ = surfaceWriter::New
         (
-            surfWriterType,
-            writeOptions.subOrEmptyDict(surfWriterType)
+            writerType,
+            surfaceWriter::formatOptions
+            (
+                sampleDiskDict,
+                writerType,
+                "writeOptions"
+            )
         );
 
         // Use outputDir/TIME/surface-name

src/functionObjects/utilities/areaWrite/areaWrite.C

@@ -181,7 +181,7 @@ bool Foam::areaWrite::read(const dictionary& dict)
 
     const dictionary writerOptions
     (
-        dict.subOrEmptyDict("formatOptions").subOrEmptyDict(writerType)
+        surfaceWriter::formatOptions(dict, writerType)
     );
 
     for (const word& areaName : meshes_.keys())