Investigate using a single root jest config

[luxaritas]

Just like we have one .eslintrc.js at the root of the repo, we may be able to manage all of our jest configuration once, removing the need to have an additional config file in each package. Will need to verify 1) that it will properly resolve and 2) that we can set things up so that projects with different setups (eg, node vs vue) can all work properly from one config. Will need to look into the projects configuration

[luxaritas]

Looks like I misunderstood what I saw - jest looks recursively upwards until it sees either a jest config or a package.json, even if the package.json doesn't contain a config. Looks like we have to do per-package configs.

[luxaritas]

For reference, related code in the jest codebase: https://github.com/facebook/jest/blob/1919ef13df544a968bd2d32e5d7b8a2a1c4b35d1/packages/jest-config/src/resolveConfigPath.ts#L86