feat(android): add group and groupSummary to LocalNotifications

[p7g]

This PR adds group and groupSummary options in LocalNotifications.schedule(), which allows you to group notifications together on Android.

I noticed a TODO comment in LocalNotificationManager.Build for groups, which says to implement setGroup, setGroupSummary, and setNumber. This PR only implements the first 2, should I also add setNumber?

[jcesarmobile]

I'm not able to make this work, can you maybe provide a sample app where I can easily test it?

Also, core-plugin-definitions.ts have now conflicts (probably because I merged your iOS PR). Can you fix it and also document that those are Android only and a brief description (for the 4 new options)

[p7g]

@jcesarmobile Here is a demo app I threw together: https://github.com/p7g/capacitor-android-group-demo

Just run it in the android emulator, send some notifications with a group name, and then send a groupSummary notification with the same group (I put a text box and some buttons on the page). That's essentially the use-case I have.

[jcesarmobile]

Thanks for the sample app, I got it working.

You have removed group and groupSummary from PushNotification types, but you are putting them in getDeilveredNotifications in PushNotifications.java. getDeilveredNotifications returns a PushNotification, so they types should have group and groupSummary, or make getDeilveredNotifications not return the group and groupSummary

[p7g]

Whoops, didn't mean to remove those, I've added them back.

[jcesarmobile]

can you also add the Android only comments as on the LocalNotification ones?

[jcesarmobile]

Looks good!
And thanks for making all the changes