Develop spatial workshop neighborhood analysis submodule

[sjspielman]

This epic tracks work to develop the fourth spatial workshop submodule on neighborhood analyses, potentially at the cell level (e.g. with Visium HD segmentation data).

Goals for this epic include:

• Outline instruction notebook
• Complete 4 instruction notebook
• Outline 4 exercise notebook
• Complete 4 exercise notebook
• Maintain spatial module cheatsheet