This PR is a follow up to #5119 which had the names backwards.
I fixed the variable names to avoid the confusion since "new" and "old" were ambiguous.
I also removed the incorrect deprecation message from packages published during commit c9597dc199.
We deprecated all the `now` scoped packages in favor of the `vercel` equivalents, however the deprecation message disappears after each publish, so we must to run `npm deprecate` after `npm publish` for legacy packages.
We want to make sure the bin matches the [installed package name](https://docs.npmjs.com/files/package.json#bin).
This means `npm i -g now` will remain `now` and `npm i -g vercel` will use `vercel` as the binary name.
This allows support for different versions on one machine such as `npm i -g now@17 vercel@19` for example.
In addition, we will also install a shorthand `vc` so you can do `vc env pull` for example.
https://vercel.com/blog/zeit-is-now-vercel
* Updates all org packages from `@now` to `@vercel`
* Updates Now CLI package name from `now` to `vercel`
* Packages contains `"bin"` entries for _both_ `vercel` and `now` in the package.json
* Updates `now-client` package name to `@vercel/client` (org scoped, for authenticity)
There is also a new `publish-legacy.sh` script which ensures that all the legacy package names (i.e. `now`, `now-client`, `@now/node`, etc.) will still be published as well.
We will remove this legacy publishing logic on Jan 1, 2021.
