Notification access and notification listener policy

The notification access and notification listener policy covers the following permission and configuration.

• The ACCESS_NOTIFICATIONS privileged permission allows an app to read the current set of notifications, including any metadata and attached intents.
• An app can be designated as a default notification listener by adding its package name to config_defaultListenerAccessPackages in config.xml or any OEM overlays. A default notification listener is granted access to all incoming notifications, but access to notifications can be turned off by users in the Notification Access settings in the Settings app.