Refactoring how view types are created and registered with ParaView.

This commits simplifies how views are added to ParaView. In past, we
need to create a pqView subclass and then add that using
pqViewModuleInterface implementation. After this change, one can add new
view types by simply defining new proxy types under the "views" group.
If you need to add a pqView subclass, or specify a pqView subclass to
use with your new view type, simply use add_pqproxy() macro, instead of
add_paraview_view_module() macro. Label used for the view is now
garnered from the proxy itself (vtkSMProxy::GetXMLLabel()).

Updating plugins, examples to use this new code.

Removed pqStandardViewModules since it's no longer relevant. If you're
using that class, simply remove it from your code and ParaView will
continue to work as expected.

Moved view XML definitions that were "internal" to "internal_views"
group. This keeps the list of "available" views clean. Plugins may have
to be updated if they are using "ViewBase" proxy definition.

Change-Id: I15b329ea13ce526ca3c1fe016da0201ac5826355
Merge topic '14744_cleanup_views' into next

7091737a Refactoring how view types are created and registered with ParaView.