Start extension host debug instance without Yarn

[colin-grant-work]

What it does

Before the switch to NPM, the extension host plugin setup for Electron used Yarn's wrapping of the node_modules/.bin binaries to invoke the theia command. With the switch to NPM, that no longer works, and extension host debugging doesn't successfully launch a new window in Electron. This PR adds a script to the Electronpackage.json to invoke theia start with no additional arguments and then uses it in the extension host debug startup process.

How to test

1. Attempt to debug a VSCode extension in Theia's electron app.
2. An extension host window should pop up and you should be able to debug your extension.

Follow-ups

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[tsmaeder]

@colin-grant-work while this works in the electron example, it does not help for Theia IDE, where npm is not available. @sgraband didn't you work on a fix for this once?

[tsmaeder]

Found the issue: eclipse-theia/theia-ide#281

[tsmaeder]

@colin-grant-work since plugin-dev is a package that can be consumed by adopters, anything using npm is not the right fix, IMO, since npm will not be available at run time. We really need to figure out the correct start incantation for starting the plugin host, like we do in the browser case.

[colin-grant-work]

I was suspicious of this solution - and suspicious of its previous yarn iteration - I'll see whether I can track down a more generally applicable mechanism.

[sgraband]

@colin-grant-work Here is a PR (i ran out of time and ideas back then) with some feedback of @tsmaeder: eclipsesource#96

Maybe this helps.