ENH: place more patch field attributes under template invariant Base

- attributes such as assignable(), coupled() etc

- common patchField types: calculatedType(), zeroGradientType() etc.
  This simplifies reference to these types without actually needing a
  typed patchField version.

ENH: add some basic patchField types to fieldTypes namespace

- allows more general use of the names

ENH: set extrapolated/calculated from patchInternalField directly

- avoids intermediate tmp

src/finiteVolume/fields/fvPatchFields/basic/transform/transformFvPatchField.H

@@ -113,16 +113,10 @@ public:
         ) const = 0;
 
 
-    // Member functions
+    // Member Functions
 
-        // Attributes
-
-            //- Return true if the value of the patch field
-            //  is altered by assignment
-            virtual bool assignable() const
-            {
-                return true;
-            }
+        //- True: this patch field is altered by assignment.
+        virtual bool assignable() const { return true; }
 
 
         // Evaluation functions