fix: default export a function in global script

[simonhaenisch]

Currently, the ionic-pwa-toolkit starter fails to build (at least with @stencil/core@1.3.0 but I think already before that) because of the ionicons dependency:

[ ERROR ]  Global Script: node_modules/ionicons/dist/collection/global.js
           The code to be executed should be placed within a default function that is exported by the global script.
           Ensure all of the code in the global script is wrapped in the function() that is exported.

To fix that, this PR:

• bumps Stencil to 1.3.0
• wraps the global script code in a function that is default exported
• fixes the build script order

For the last point, please check whether that's ok. The reason is that I wasn't able to build the project because the icons folder was missing until the build.data script had been run (which generates that icons folder. Might be related to 8839341.

---

To make the pwa-toolkit starter work again, the following actions have to be taken:

• merge this PR and make a release
• update the ionicons dependency in the @ionic/core package
• release a new @ionic/core version
• update the @ionic/core dependency in ionic-pwa-toolkit