Fix vtkPlaneCutter's Memory Leak and CopyStructure issues

vtkPlaneCutter now frees the sphere-trees if the input changes, and it can handle vtkUniformGridAMR.

Additionally, vtkPlaneCutter used to produce a vtkMultiPieceDataSet for each input (sub-)dataset. For complex vtkMultiBlockDataSet this led to CopyStructure issues. That's why now vtkAppendPolyData is utilized to merge the threaded results. Due to this change, the output type also changes as follows:

• If input type is vtkMultiBlockDataSet, the output type will be vtkMultiBlockDataSet.
• If input type is vtkUniformGridAMR, the output type will be vtkPartitionedDataSetCollection.
• If input type is vtkPartitionedDataSetCollection, the output type will be vtkPartitionedDataSetCollection.
• If input type is vtkPartitionedDataSet, the output type will be vtkPartitionedDataSet.
• If input type is vtkDataSet, the output type will be vtkPolyData.

In the past, the output type was as follows:

• If input type is vtkUniformGridAMR or vtkMultiBlockDataSet, the output type will be vtkMultiBlockDataSet.
• If input type is vtkPartitionedDataSetCollection, the output type will be vtkPartitionedDataSetCollection.
• If input type is vtkDataSet or vtkPartitionedDataSet, the output type will be vtkPartitionedDataSet.

This MR resolves issue paraview/paraview#21250 (closed).