session: add scrim

modules/drawers/Drawers.qml

@@ -55,6 +55,20 @@ Variants {
                 }
             }
 
+            StyledRect {
+                anchors.fill: parent
+                opacity: visibilities.session ? 0.5 : 0
+                color: Colours.palette.m3scrim
+
+                Behavior on opacity {
+                    NumberAnimation {
+                        duration: Appearance.anim.durations.normal
+                        easing.type: Easing.BezierSpline
+                        easing.bezierCurve: Appearance.anim.curves.standard
+                    }
+                }
+            }
+
             Item {
                 id: background