Unsupported extension developer journey: run debug mode devtools with debug mode extension

Right now, the only way to test your extension in debug mode is using the simulated devtools environment. However, if you want to test your extension in DevTools there is not currently an easy way to do this with both devtools and the extension in debug mode.

Here a workaround I recommended to a user for the meantime, although this is untested:

> In the meantime, I think you can run your devtools extension in debug mode, and then change this url to be the url of your locally running debug DevTools extension:
> https://github.com/flutter/devtools/blob/master/packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart/#L42-L43
> and flip debugDevToolsExtensions to true. Then you should be able to run DevTools in debug mode on chrome and see your debug mode DevTools extension in the iFrame.