(implemented, locked) Factoring out rationale

[quinn-dougherty]

rationale is a dead repo, an artefact from the reason days, and according to Sam seems like it's the thing that forces us to build with -with-deps flag, creating friction to packaging on npmjs.

Eventually we'll want to remove this dependency, as the packaging process is important for our overall theory of change-- seamless integration of squiggle into websites far and wide.

[Hazelfire]

That's not true. Almost all Rescript dependencies requires calling -with-deps sadly. Rescript users don't really seem to consider having pre compiled code in their npm packages. Rationale is currently not holding us back in any way that I see, other than maybe being able to publish non-bundled code (which wouldn't be useful, because we need bundled code for it to work in observable)

[quinn-dougherty]

This is now story #410 to be done ASAP