Jetpack Focus: Disable Local Notifications

[staskus]

Part of #19531

This task can be branched from and merged into #19531 to support disabling both local and remote notifications.

Task

Disable local notifications on the WordPress app when Jetpack is installed and has notifications enabled.

#19531 implements disabling of push notifications using NotificationServiceExtension. However, this extension is only triggered by remote notifications and cannot be used to filter local notifications.

Potential solution

Use wordPressNotificationsEnabled flag created in #19531 and avoid scheduling new WordPress local notifications based on this flag.

This is only a potential solution, any solution that allows to disable local WordPress notifications from Jetpack app and avoid showing already scheduled local notifications is welcome.

[mokagio]

Pushing to 21.3. See also this comment on the PR linked in the description