[Epic] Convert to monorepo

[rekmarks]

By iterating in the approval controller, I've bumped us up two major versions, and with #321, it will be a third. We should publish all controllers as individual packages, and turn this into a monorepo.

[brad-decker]

When using a monorepo, my preferred practice for packages is to keep the versions linked so that there is never a discrepancy in version number across packages. React, and babel are good examples of this. I don't think we want our controllers in different version states; thus, it might not solve the particular problem stated in the description.

[brad-decker]

This would also require a significant rethinking of the messaging proposal to have each controller in its separate package.

this is already necessary, but the original comment stands. :D

[mcmire]

Converting this repo into a monorepo (with all controllers placed into their own package) is now a goal of the newly established core team and it is something we will be aiming to complete by end of Q2.

As it relates to the discussion above, we have decided that we do not want to synchronize versions among all of the packages in this repo. Eventually, this repo will be renamed core and will house other packages which are not related to controllers. We want to be able to give ourselves and product teams the independence to maintain packages with as little coupling as possible.

Consult this document for more information on our plan going forward.

[Gudahtt]

This was completed in #831