webpack-cli throws 'Unknown option' error when using --superset arg

[jdbranham]

A clear and concise description of what the bug is.

How to reproduce the bug

1. execute the example command from -
   https://github.com/apache/superset/blob/master/CONTRIBUTING.md#webpack-dev-server

npm run dev-server -- --superset=https://my-superset

Expected results

Webpack dev server should proxy to the remote superset backend.

Actual results

Error is thrown -
[webpack-cli] Error: Unknown option '--superset=https://my-superset'

Environment

• browser type and version: Chrome [NA]
• superset version: master
• python version: 3.9.10
• node.js version: v16.14.2
• any feature flags active: none

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

[vivostar]

@jdbranham wow! thanks for your contribution, your patch fix my building dev enviroment problem. I think the patch should be merged into Main Branch