Tweak how we populate NavBarItems.

Now we will always place child items of a node in the right bar, even if we're
also placing it on the 'top level nodes' list on the left.  This makes things
clearer for users by making it clear that any time you have a node selected on
the left, you can always find its children on the right.  And, it still preserves
the behavior we want where the left list acts as a high level 'table of contents'
for the file.
1) No.  Because it's up to the language if it wants to be sorted or not.  The navbars are just a list of items.
2) Even if it was, there is no way for view to know how to sort this.  Recall that you have something akin to

```
<global>
    class C
    interface I
```
Just trying to sort that by text would be <global> at the bottom as both of the 'child' items start with spaces/indents.