Migrate to create-* npm package

[flut1]

Yarn has a create command that will install a npm package globally and then run its binary. I think we should consider migrating seng-boilerplate to work with this format, for multiple reasons:

• Running a script is quicker than manually checking out a repository and renaming the folder
• Having the script be accessible through a quick yarn create command, and additionally being able to run it through npx create-*, is even easier to use
• Currently, a lot of find/replace has to be done to remove occurrences of seng-boilerplate and replacing them with the new package name. This costs a lot of time. Ideally, this is automated with a CLI
• Some replacements are often overlooked. Most notably, the license file, which should definitely not always be copied verbatim.
• Publishing our boilerplate to a repository may allow us to offload certain configuration to a separate package, similarly to create-react-app. This will allow us to more easily upgrade tooling in libraries created using seng-boilerplate.

[ThaNarie]

We already have a yeoman generator that takes care of the first 4 points this automatically, although I don't mind supporting yarn/npx that way if it's more convenient.

If we do the last bit, we would also need an eject option, but I think that's something for a separate ticket.

[flut1]

I forgot one of my most important points:

• The readme currently doesn't reflect the boilerplate itself. It represents the template for new packages.

I get that this can also be resolved using a yeoman generator, but I think the readme that comes up at the "homepage" of the github repository when you look it up, should be a clear explanation of what the boilerplate is rather than a template file.

[flut1]

If we do the last bit, we would also need an eject option

this is indeed a future discussion (something for a separate ticket), but in my view I would definitely be more conservative than create-react-app with how many configuration would be offloaded to separate packages. create-react-app is targeted at a different audience, and I don't think our boilerplate really needs to be as accessible, as it is aimed at library developers. It would already be a win to only move the dev-dependencies to a separate package (so not the config itself, just the dependency), so that we can more easily do security updates.