refs https://github.com/TryGhost/DevOps/issues/50
- `react-app` comes from `eslint-config-react-app`, which is a CRA package
- we're moving away from that so this commit switches the linting over
to a more recently updated plugin
- once that was removed, we started using a newer version of
`@typescript-eslint/eslint-plugin`, so there were plenty of
updates/exemptions to make
refs https://github.com/TryGhost/DevOps/issues/50
- this switches the .eslint configs from `node` to `ts`, which is a new
config to support eslint for TypeScript
- also makes minor changes to adhere to these new rules
refs https://github.com/TryGhost/DevOps/issues/45
- this switches the monorepo over to using Nx instead of Lerna, because
we don't currently need the versioning+publishing capabilities
- this also adds an `nx.json`, which allows us to enable task caching
- also adds `build:ts` to the TS projects, which is cached for fast execution
- how these interact with the dev.js script will hopefully soon be
reworked to be a better experience
refs https://github.com/TryGhost/DevOps/issues/45
- this moves the bulk of the tsconfig file to the `ghost/` folder and
simply extends this file in each of the TS lib packages we currently
have
- this makes it a lot easier to make single changes to our TS config
