Use the official npm package for local-notifications plugin

A while ago we decided to use our own npm package for the local-notifications plugin because the official one wasn't in npm. Now it is, so we should use that one. This is the package:

https://www.npmjs.com/package/de.appplant.cordova.plugin.local-notification

In our fork we tried to fix the error of notifications showing when the device was rebooted. I see that the official repo now has a commit saying that they fix some notifications show on reboot, so maybe they fixed it too but using a different approach. We should test it.

Also, we should use the property "text" instead of "message" (deprecated).