timeLimitsManager: Simple split of enabled setting in two

As described and motivated in
https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/3306, it
turns out that we want to be able to save screen time usage data while
not enabling limits based on that usage.

Bump the shell’s dependency on gsettings-desktop-schemas to get the
split setting, and roughly adapt the existing `timeLimitsManager` code
to use the new setting names. The code currently treats the two settings
as equivalent / expects them both to be set the same. The following
commits will refine that behaviour.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/3306
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3610>

js/misc/timeLimitsManager.js

@@ -168,7 +168,7 @@ export const TimeLimitsManager = GObject.registerClass({
     }
 
     _updateSettings() {
-        if (!this._screenTimeLimitSettings.get_boolean('enabled')) {
+        if (!this._screenTimeLimitSettings.get_boolean('history-enabled')) {
             if (this._state !== TimeLimitsState.DISABLED) {
                 this._stopStateMachine().catch(
                     e => console.warn(`Failed to stop state machine: ${e.message}`));