[qml] Optimize QML files and fix syntax warnings

This commit addresses warnings that were raised by QtCreator's linter:
- IDs declared more than once
- variables declared more than once in the same scope
- type coercions
- variables declared as "var" when their type is known
- unclosed "case" in switch-case

meshroom/ui/qml/Utils/SortFilterDelegateModel.qml

@@ -70,7 +70,7 @@ DelegateModel {
     function find(value, roleName) {
         for(var i = 0; i < filteredItems.count; ++i)
         {
-            if(modelData(filteredItems.get(i), roleName) == value)
+            if(modelData(filteredItems.get(i), roleName) === value)
                 return i
         }
         return -1