ENH: provide dictionary access for coded BCs etc (#1922)

- in some cases, additional dictionary inputs are useful for extending
  the input parameters or functionality of dynamic coded conditions.

  Typically this can be used to provide a simple set of dictionary
  inputs that are used to drive specific code, but allows changing the
  inputs without causing a recompilation.

  Accessed with this type of code:
  ```
  const dictionary& dict = this->codeContext();
  ```

boundary conditions and function objects:

* specify an additional codeContext dictionary entry:
  ```
  codeContext
  {
      ...
  }
  ```

PatchFunction1:

* The code context dictionary is simply the dictionary used to specify
  the PatchFunction1 coefficients.

  To replicated persistant data, use local member static data.
  Eg,
  ```
  code
  #{
      // Persistent (Member) Data
      static autoPtr<Function1<scalar>> baseVel;
      static autoPtr<Function1<vector>> baseDir;
      ...
  #}
  ```

fvOptions:

* currently not applicable

src/functionObjects/utilities/codedFunctionObject/codedFunctionObject.C

@@ -72,6 +72,14 @@ void Foam::functionObjects::codedFunctionObject::clearRedirect() const
 }
 
 
+const Foam::dictionary&
+Foam::functionObjects::codedFunctionObject::codeContext() const
+{
+    const dictionary* ptr = dict_.findDict("codeContext", keyType::LITERAL);
+    return (ptr ? *ptr : dictionary::null);
+}
+
+
 const Foam::dictionary&
 Foam::functionObjects::codedFunctionObject::codeDict() const
 {
@@ -157,6 +165,22 @@ Foam::functionObjects::codedFunctionObject::redirectFunctionObject() const
             time_,
             constructDict
         );
+
+
+        // Forward copy of codeContext to the code template
+        auto* contentPtr =
+            dynamic_cast<dictionaryContent*>(redirectFunctionObjectPtr_.get());
+
+        if (contentPtr)
+        {
+            contentPtr->dict(this->codeContext());
+        }
+        else
+        {
+            WarningInFunction
+                << name_ << " Did not derive from dictionaryContent"
+                << nl << nl;
+        }
     }
     return *redirectFunctionObjectPtr_;
 }

src/functionObjects/utilities/codedFunctionObject/codedFunctionObject.H

@@ -44,6 +44,7 @@ Description
        codeExecute | c++; upon functionObject::execute()
        codeWrite   | c++; upon functionObject::write()
        codeEnd     | c++; upon functionObject::end()
+       codeContext | additional dictionary context for the code
     \endplaintable
 
 Usage
@@ -67,6 +68,10 @@ Usage
     }
     \endverbatim
 
+Note
+    The code context dictionary can be supplied separately as the
+    \c codeContext entry.
+
 See also
     Foam::functionObject
     Foam::codedBase
@@ -128,6 +133,9 @@ protected:
         //- Clear redirected object(s)
         virtual void clearRedirect() const;
 
+        //- Additional 'codeContext' dictionary to pass through
+        virtual const dictionary& codeContext() const;
+
         //- The code dictionary
         virtual const dictionary& codeDict() const;