Run "yarn rw-gen" during create redwood app

[jtoar]

TypeScript Redwood Apps (created with yarn create redwood-app --ts) can't find the NotFoundPage in the Routes.tsx file because the types haven't been generated yet (#2754). This PR fixes this by generating the types as a part of the install.

I think the types are supposed to help JS projects too, so I made it so that they're generated for JS projects as well on install.

[thedavidprice]

One area where our create-redwood-app.js script fails is that we assume yarn install is always run. But we provide an option for --no-yarn-install, which, if used alone, will cause the script to fail because it tries to convert to TS using yarn rw ts-to-js. (One simple way to improve this is to set the condition to only run ts-to-js command if --yarn-install=true. I think a better solution would be to include the TS to JS transformation as a step in the installation script so that it could run whether or not yarn is installed.)

I'm curious if we'll have the same issue here where --no-yarn-install is passed but then the script fails because it can't generate the types... possibly?

[peterp]

Nice! Maybe we can add skip to the listr tasks if the install flag isn't present?

[jtoar]

@thedavidprice linking #1954 just cause you mentioned that there too, and it does indeed fail if yarn install isn't true which is definitely not ideal.

I think a better solution would be to include the TS to JS transformation as a step in the installation script so that it could run whether or not yarn is installed

^ I'll see if I can include this here

[peterp]

@jtoar Could you try the ts-stuff in a different PR? I would like to get this one in alongside the eslint PR.

[jtoar]

@peterp Absolutely; I can go ahead and rebase this one it if it looks ready

[jtoar]

I included a check for --yarn-install just for now, so that it generates a TS project if --yarn-install=false (instead of failing). I did it via Listr's enabled property, but I could also do it via skip and provide a message:

enabled: () => typescript === false,
skip: () => {
  if (yarnInstall === false) {
    return 'skipped; needs ts-to-js binary'
  }
},

[peterp]

Woot!

[dac09]

LGTM too!