Add autoplot() methods for classes of persistence and other topological data

[rrrlw]

e.g. fortify_ripserr() for persistence data output by ripserr

[corybrunson]

fortify() has for a while been threatened with deprecation. While {broom} tools like tidy() might be out of place here, autoplot() methods for classes like 'PHom' and 'diagram' would be appropriate.

• 'diagram' ({TDA})
• 'PHom' ({ripserr})
• 'Rtsne' ({Rtsne})
• 'umap' ({umap})