ITKMorphologicalWatershedFromMarkersImageFilter wrapper is incomplete (no marker-image input)

## Summary

The `ITKMorphologicalWatershedFromMarkersImageFilter` wrapper is incomplete: a marker-controlled watershed requires **two** inputs, but the simplnx wrapper exposes only one.

## Details

ITK's `itk::MorphologicalWatershedFromMarkersImageFilter` takes two images:
1. the image to flood (typically a gradient/edge image), and
2. a **marker (seed) label image** that imposes the minima and supplies the output labels.

The simplnx wrapper (`src/Plugins/ITKImageProcessing/src/ITKImageProcessing/Filters/ITKMorphologicalWatershedFromMarkersImageFilter.{hpp,cpp}`, UUID `9bfcf09b-b510-4d46-982c-d2e35dedefdf`) only exposes a single `Input Cell Data` array (`k_InputImageDataPath_Key`) plus `Mark Watershed Line` and `Fully Connected`. There is **no parameter for the marker image**, so as wrapped the filter cannot perform a marker-controlled watershed.

## Current state

- The filter is **already excluded from the build**: it is not in the active `FilterList` in `src/Plugins/ITKImageProcessing/CMakeLists.txt` (only a commented entry, in the "These filters need to have their type or dimension fixed" section). `create_simplnx_plugin` compiles strictly from `FilterList`, so the filter is neither compiled nor registered.
- However, the orphaned source files (`.hpp`/`.cpp`) and a documentation page (`src/Plugins/ITKImageProcessing/docs/ITKMorphologicalWatershedFromMarkersImageFilter.md`) remain in the repository. The doc is still published even though the filter is not shipped.

## Recommendation

Either:
- **(a)** complete the wrapper so it accepts a separate marker (label) image input, then re-enable it in `FilterList`; or
- **(b)** remove the orphaned source and documentation files if the filter is not going to be supported.

Found during the Batch 8 ITK documentation review.

Start with src/Plugins/ITKImageProcessing/src/ITKImageProcessing/Filters/ITKMorphologicalWatershedFromMarkersImageFilter.hpp and .cpp, then inspect the commented entry in src/Plugins/ITKImageProcessing/CMakeLists.txt and the documentation page. Decide whether to add the marker-image input and re-enable the filter, or remove the orphaned source and documentation. Done means the unsupported state is resolved and the FilterList and published documentation agree.

Written by the indexing model from the issue text.