DOC: Fix unbalanced grouping commands Doxygen warnings

Fix unbalanced grouping commands Doxygen warnings.

Fixes:
```
Modules/Core/Common/include/itkAutoPointer.h:261: warning: unbalanced grouping commands
```

warnings across classes.

The warning is raised when the
Utilities/Doxygen/itkdoxygen.pl

Doxygen Perl script processes the files at issue and starts a `/**@{`
block that gets interrupted by an unexpected symbol (e.g. a brace)
without being previously closed with the corresponding `/**@}*/`
ending token.

Raised for example in:
https://open.cdash.org/viewBuildError.php?type=1&buildid=8344134

Author: jhlegarreta

Modules/Core/Common/include/itkAutoPointer.h

@@ -254,6 +254,7 @@ TransferAutoPointer(TAutoPointerBase & pa, TAutoPointerDerived & pb)
     pb.ReleaseOwnership(); // pb Release Ownership and clears
   }
 }
+
 } // end namespace itk
 
 #endif

Modules/Core/Common/include/itkBSplineDerivativeKernelFunction.h

@@ -186,6 +186,7 @@ class ITK_TEMPLATE_EXPORT BSplineDerivativeKernelFunction : public KernelFunctio
     itkGenericExceptionMacro("Evaluate not implemented for spline order " << SplineOrder);
   }
 };
+
 } // end namespace itk
 
 #endif

Modules/Core/Common/include/itkBSplineInterpolationWeightFunction.h

@@ -122,6 +122,7 @@ class ITK_TEMPLATE_EXPORT BSplineInterpolationWeightFunction
   BSplineInterpolationWeightFunction() = default;
   ~BSplineInterpolationWeightFunction() override = default;
 };
+
 } // end namespace itk
 
 #ifndef ITK_MANUAL_INSTANTIATION

Modules/Core/Common/include/itkBSplineKernelFunction.h

@@ -180,6 +180,7 @@ class ITK_TEMPLATE_EXPORT BSplineKernelFunction : public KernelFunctionBase<TRea
     itkGenericExceptionMacro("Evaluate not implemented for spline order " << SplineOrder);
   }
 };
+
 } // end namespace itk
 
 #endif

Modules/Core/Common/include/itkBackwardDifferenceOperator.h

@@ -73,6 +73,7 @@ class ITK_TEMPLATE_EXPORT BackwardDifferenceOperator : public NeighborhoodOperat
     this->FillCenteredDirectional(coeff);
   }
 };
+
 } // namespace itk
 
 #ifndef ITK_MANUAL_INSTANTIATION

Modules/Core/Common/include/itkBufferedImageNeighborhoodPixelAccessPolicy.h

@@ -126,6 +126,7 @@ class BufferedImageNeighborhoodPixelAccessPolicy final
   {
     m_NeighborhoodAccessor.Set(imageBufferPointer + m_PixelIndexValue, pixelValue);
   }
+
 };
 
 } // namespace itk

Modules/Core/Common/include/itkCommonEnums.h

@@ -164,6 +164,7 @@ using IOFileModeType = CommonEnums::IOFileMode;
 using IOByteOrderType = CommonEnums::IOByteOrder;
 using CellGeometryType = CommonEnums::CellGeometry;
 #endif
+
 // Define how to print enumeration
 extern ITKCommon_EXPORT std::ostream &
                         operator<<(std::ostream & out, IOPixelEnum value);

Modules/Core/Common/include/itkConnectedImageNeighborhoodShape.h

@@ -83,6 +83,7 @@ namespace itk
  * \ingroup ImageIterators
  * \ingroup ITKCommon
  */
+
 template <unsigned int VImageDimension>
 class ConnectedImageNeighborhoodShape
 {
@@ -247,8 +248,8 @@ class ConnectedImageNeighborhoodShape
   {
     return (includeCenterPixel ? 1 : 0) + CalculateNumberOfConnectedNeighbors(maximumCityblockDistance);
   }
-};
 
+};
 
 /** Generates the offsets for a connected image neighborhood shape. */
 template <unsigned int VImageDimension, size_t VMaximumCityblockDistance, bool VIncludeCenterPixel>

Modules/Core/Common/include/itkConstantBoundaryImageNeighborhoodPixelAccessPolicy.h

@@ -144,8 +144,8 @@ class ConstantBoundaryImageNeighborhoodPixelAccessPolicy final
       m_NeighborhoodAccessor.Set(imageBufferPointer + m_PixelIndexValue, pixelValue);
     }
   }
-};
 
+};
 
 } // namespace itk
 

Modules/Core/Common/include/itkContinuousIndex.h

@@ -90,6 +90,7 @@ class ITK_TEMPLATE_EXPORT ContinuousIndex : public Point<TCoordinate, VIndexDime
       (*this)[i] = static_cast<TCoordinate>(index[i]);
     }
   }
+
 };
 } // namespace itk