BioCell was the only ITKRemoteModule with a pyproject.toml but no
wrapping/ directory, causing the Python wheel build CI to fail: the
manylinux build script found no .whl to repair and exited with an error.

Add wrapping for the two itk::Object-derived classes:
- itk::bio::CellularAggregateBase (non-templated)
- itk::bio::CellularAggregate<2> and <3>

Adding this simple wrapping allows the standard python wrapping
infrastructure to be tested and consistent with other remote modules.

Generative AI was used to diagnose and recommend this solution.

The ITK wrapping machinery derives include filenames from the class name
by stripping all but the leaf name: itk::bio::CellularAggregate ->
itkCellularAggregate.h. The actual headers use the Bio prefix
(itkBioCellularAggregate.h), causing castxml to abort with
"file not found".

Add explicit itk_wrap_include() directives so the generated castxml
input files include the correct headers.

Generative AI was used to diagnose and recommend this solution.

Three issues prevented the Python wrapping from building:

1. WRAPPER_AUTO_INCLUDE_HEADERS was ON, causing itk_wrap_class to
   auto-derive wrong header filenames (itkCellularAggregateBase.h
   instead of itkBioCellularAggregateBase.h). Disable auto-include
   and rely on the explicit itk_wrap_include() directives, matching
   the pattern used by Ultrasound (BlockMatching) and ITK Statistics.

2. CellularAggregateBase is a non-template class but was wrapped with
   itk_wrap_class/itk_end_wrap_class (no itk_wrap_template calls),
   producing an empty SWIG interface. Use itk_wrap_simple_class
   instead so the class is properly registered.

3. itk_auto_load_submodules() processes .wrap files alphabetically,
   causing CellularAggregate to load before its base class. Add
   WRAPPER_SUBMODULE_ORDER to enforce correct dependency ordering.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>