Deprecated the `CellLocator` class and made all methods of the
other `CellLocator` classes non-virtual. General locators can
still use the `CellLocatorGeneral` class, but this class now
only works with a predefined set of locators. (The functionality
to provide a function to select a locator has been removed.)
The circular dependency came from UnknownArrayHandle.h needing
VTKmDefaultTypes.h, which needed all the cell set types. Some of those
cell sets used ArrayCopy in templated functions. Changed those functions
to directly deep copy the ArrayHandle.
