Fixes: U4-3442 tree sync doesn't work for nodes that are not loaded - tree sync is now working properly and loads in any nodes that are missing. Have removed the dependency on navigationService from umbTree directive since it should not have that dependency. navigationService now sets it's global current node after treeSync based on an event. Moved the treeSync logic to the treeService so it can be unit tested (now to write the unit tests). Added another method to treeService to reload a single node - this is now used by treeSync when the current node is being synced - much nicer than reloading all the children.  Updates the treeService to always add the current section to each tree node, this will make it much easier to know the treenode section - and in theory should mean we might be able to remove the ui global currentSection var.