When testing against closure, RxJS will be re-compiled to target ES2015 modules.
The RxJS tsconfig file takes all `@types` that are installed and due to a recent update of the gulp types, building RxJS fails now.
* build: use shared logic to build packages
* No longer creates the whole set of gulp tasks just to build a single package.
* Makes the package building & releasing more consistent. No extra `build:release` just for the `lib` package.
References #4108
* Address feedback
* Due to the TSConfig file renaming in #3791 and the fact that they were merged at the same time, the path in the closure-compiler script is now invalid.
* build: run closure-compiler
* Adds a script that runs the closure-compiler against the devapp / demo-app.
* The script will run on the CI as a new mode. Ensuring that all our components are closure-compatible.
Fixes#1206.
* Address feedback
Paul Gschwendtner