Modernization

[jesseditson]

This PR Builds on #31, integrating @nzapponi's original commit and taking it a bit further:

• remove some deps that are not fair assumptions for all live apps:
  • ajv (unused)
  • @babel/plugin-proposal-class-properties (inheriting apps should explicitly define if they are using this)
  • @babel/polyfill (deprecated, added core-js and regenerator-runtime to fill the same needs)
  • moment (unused)
  • webpack-cli, webpack-dev-server (inheriting apps should just list these as deps. We can add as peerDependencies if it's not obvious)
  • quip-apps-compat (may add back, but want to get our testing story clean without it since it's kind of a hack)
• respect inheriting apps' .babelrc if provided
• update to latest version of all deps
• run quip prettier on webpack.config.js

[jesseditson]

The most contentious decision in this PR is the removal of quip-apps-compat, which I would propose we remove in favor of some explicit mocks that can be imported in dev/test and which properly respect quip's globals when they exist. This way we wouldn't have any magic globals and we can use jest and other tooling that does not use webpack (closer to) out of the box. I'll build those mocks and either add them to this PR or file a separate one.

[jesseditson]

@elsigh I'm gonna merge this one now since I've been testing it over on https://github.com/quip/quip/pull/4924 and it's at a point where I trust it while linked, and would like to publish it to a next tag. Unless you tell me otherwise I'll be publishing all of the quip-apps as 1.0.0-alpha.1 under the next tag (so they can be installed via npm i <package-name>@next but won't update existing packages).

[jesseditson]

Note that I also have a precog script that will fail commits that cause internal Live Apps API exports to be different than quip-apps-api. An additional future enhancement will be type safety, which will require typescript on both sides, which can happen once we migrate internally.