Develop spatial workshop submodule one

[sjspielman]

This epic tracks work to develop the first spatial workshop submodule on Visium data processing.
Goals for this epic include:

• Complete submodule 1 instruction notebook
• Outline submodule 1 exercise notebook, including the dataset to use
• Complete submodule 1 exercise notebook
• Establish spatial module cheatsheet

[sjspielman]

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