GCDWebServer missing in cordova-plugin-meteor-webapp

[nachocodoner]

Report: #12946

Reproduction

Fix

It seems that when we migrated the cordova-plugin-meteor-webapp from its own repository to the meteor monorepo, we missed to set up the git submodule included in the other repository.

• Add missing submodule in the cordova-plugin-meteor-webapp package
• Test fix locally by changing .meteor/cordova-plugins file of an example app and using a local path reference
• Publish a new version of npm cordova-plugin-meteor-webapp@2.0.4, https://www.npmjs.com/package/cordova-plugin-meteor-webapp
• Update default references for cordova-plugin-meteor-webapp (webapp) to use newer version including missing libraries
• Test to check if issue is fixed for a new app pointing the new npm version