breakManager: Add new state machine for screen time/health breaks
This implements health break reminder support in gnome-shell. It depends on a few bits and bobs from other modules:
- New settings schemas in gsettings-desktop-schemas
- A settings UI in gnome-control-center
- User documentation in gnome-user-docs
It implements the design from https://gitlab.gnome.org/Teams/Design/settings-mockups/-/blob/master/wellbeing/wellbeing.png.
The core of the implementation is BreakManager, which is a state
machine which uses the Mutter IdleMonitor to track whether the user
is, or should be, in a screen time break.
The BreakDispatcher is based on top of this, and controls showing
notifications, countdown timers, screen fades, the lock shield, etc. to
make the user aware of upcoming or due breaks, as per their notification
preferences.
Unit tests are included to check that BreakManager works. These
provide mock implementations of basic GLib clock functions, the
IdleMonitor and Gio.Settings in order to test the state machine in
faster-than-real-time.
Signed-off-by: Philip Withnall pwithnall@gnome.org