Add yarn rw dev option to pass any Webpack config as a string

[thedavidprice]

Fix #890

This is an alternate, mutual approach to #891 We could merge both and add to CLI docs for yarn rw dev

@peterp My approach here is to add a string option to the Yargs command, which could be used to pass any+all Webpack DevServer config options, which will override webpack.development.js.

Most importantly --> What do you this of this approach?

Secondarly --> does the code implementation pass your PeterPSniffTest™?

edit: Oh, one question. Should the name of the option be webpack-config or webpackConfig for CLI option?

[peterp]

Ooh, I love this... This is what I've wanted for a long time.

Could we make it more generic? Cause I would like to make this also work for jest, lint, etc.

Maybe something like --forward. In yarn and npm this used to just be --: yarn test -- --watchAll, but I don't think that'll work anymore.

[thedavidprice]

Yargs "Stop Parsing" Forwarder

Yargs does have an option to use -- to stop parsing and capture remainders into an array:
https://github.com/yargs/yargs/blob/master/docs/tricks.md#stop-parsing

However, when I try to run using yarn rw dev -- blahblah, it appears Yarn intercepts and throws a warning, which seems to disrupt the defaults (i.e. sides: api, web in our case):

warning From Yarn 1.0 onwards, scripts don't require "--" for options to be forwarded. In a future version, any explicit "--" will be forwarded as-is to the scripts.
...
Invalid values:
  Argument: side, Given: "blahBlahblahBlah", Choices: "api", "web"
error Command failed with exit code 1.

Bummer ☹️

[thedavidprice]

@peter this is ready to merge per your approval:

• changed the option name to forward with alias fwd
• updated description and provided a better example of use

I'm creating a PR with CLI doc update now.

[thedavidprice]

Doc updated here:
https://github.com/redwoodjs/redwoodjs.com/pull/261

[styfle]

Thanks! When can we expect a new stable release?

[thedavidprice]

@styfle By end of today!!