Add heading indicator for live locations

Heading isn't covered by any MSC so far, so that is using Itinerary's
vendor prefix for now.

src/qml/Component/FullScreenMap.qml

@@ -46,6 +46,7 @@ ApplicationWindow {
             asset: root.asset
             author: root.author
             isLive: true
+            heading: NaN
             visible: !isNaN(root.latitude) && !isNaN(root.longitude)
         }
         MapItemView {

src/qml/Component/LocationMapItem.qml

@@ -24,11 +24,14 @@ MapQuickItem {
 
     required property bool isLive
 
+    required property real heading
+
     anchorPoint.x: sourceItem.width / 2
     anchorPoint.y: sourceItem.height
     coordinate: QtPositioning.coordinate(root.latitude, root.longitude)
     autoFadeIn: false
     sourceItem: Kirigami.Icon {
+        id: mainIcon
         width: height
         height: Kirigami.Units.iconSizes.huge
         source: "gps"
@@ -55,5 +58,19 @@ MapQuickItem {
             source: root.author.avatarSource
             color: root.author.color
         }
+
+        Kirigami.Icon {
+            id: headingIcon
+            source: "go-up-symbolic"
+            color: parent.color
+            visible: !isNaN(root.heading) && root.isLive
+            anchors.bottom: mainIcon.top
+            anchors.horizontalCenter: mainIcon.horizontalCenter
+            transform: Rotation {
+                origin.x: headingIcon.width/2
+                origin.y: headingIcon.height + mainIcon.height/2
+                angle: root.heading
+            }
+        }
     }
 }

src/qml/Component/LocationPage.qml

@@ -36,6 +36,7 @@ Kirigami.Page {
             }
             delegate: LocationMapItem {
                 isLive: true
+                heading: NaN
             }
         }
 

src/qml/Component/Timeline/LocationDelegate.qml

@@ -57,6 +57,7 @@ TimelineContainer {
                 asset: root.asset
                 author: root.author
                 isLive: true
+                heading: NaN
             }
 
             TapHandler {