polyMeshDistributionMap: renamed mapDistributePolyMesh -> polyMeshDistributionMap

This is a map data structure rather than a class or function which performs the
mapping operation so polyMeshDistributionMap is more logical and comprehensible
than mapDistributePolyMesh.

etc/codeTemplates/dynamicCode/codedFvModelTemplate.C

@@ -187,7 +187,7 @@ void ${typeName}FvModel${SourceType}::updateMesh(const mapPolyMesh& map)
 
 void ${typeName}FvModel${SourceType}::distribute
 (
-    const mapDistributePolyMesh& map
+    const polyMeshDistributionMap& map
 )
 {
     set_.distribute(map);