integrate proofs in the documentation site

[Shoeboxam]

Closes #56

• .gitignores generated python modules to avoid spurious diffs of local doc links to proofs
  • adjusts CI to save bindings as an artifact, or generate them with cargo check
• updated docs.yml workflow to generate all proof pdfs and upload to opendp/artifacts upon merge to main or release
• updated docs.yml to copy proof artifacts to gh-pages docs site's multiversion folders
• source code links in docs.opendp.org for automatically generated functions go to the same function in docs.rs
• support for rendering katex in the rustdocs
  • added an opendp_tooling/katex.html that replaces latex in $inline$ and ```math sections
  • updated developer documentation to inject the html file
  • a VSCode task for building rustdocs with latex
  • added a Cargo.toml directive for docs.rs to render with katex injected
• renamed mod.sty to lib.sty, as this style file sits in the root next to lib.rs
• latex macro for generating a link to either pdf file or rust doc
  • this is used in the make_count.tex PR, check out the rendered pdf

This should give us all the pieces we need to continuously browse proofs/documentation across python, rust and latex, with versioned links and support for offline builds.