Improve location marker

Change location marker to GPS icon, make sure the point is the anchor and colour it with highlight colour

m.self \
![image](/uploads/d7136e7f70a106665fcaea0588a334f7/image.png)

m.pin \
![image](/uploads/baee5d19c098eaab1abd91533fe431e5/image.png)

src/models/messageeventmodel.cpp

@@ -71,6 +71,7 @@ QHash<int, QByteArray> MessageEventModel::roleNames() const
     roles[IsPendingRole] = "isPending";
     roles[LatitudeRole] = "latitude";
     roles[LongitudeRole] = "longitude";
+    roles[AssetRole] = "asset";
     return roles;
 }
 
@@ -835,6 +836,14 @@ QVariant MessageEventModel::data(const QModelIndex &idx, int role) const
         return latitude.toFloat();
     }
 
+    if (role == AssetRole) {
+        const auto assetType = evt.contentJson()["org.matrix.msc3488.asset"].toObject()["type"].toString();
+        if (assetType.isEmpty()) {
+            return {};
+        }
+        return assetType;
+    }
+
     if (role == ReadMarkersRole) {
 #ifdef QUOTIENT_07
         auto userIds = room()->userIdsAtEvent(evt.id());