Smooth arclength interpolation (#404)

* POC

* Transfer most of the notebook to the docs

* Delete arclength_interpolation.ipynb

* Update docs/make.jl

* Add tests

* Cleanup code and add docstrings

* Remove project.toml

* Bring back inverting integrals docs

* Update Project.toml

* Move back docs project.toml

* Fix tests

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Co-authored-by: Christopher Rackauckas <accounts@chrisrackauckas.com>

Author: SouthEndMusic