Filter of type location types, indicator of long tasks in NaviBar

The following suggestions are posted by @fitdev in comment of #67 :

1. Is it possible to introduce some way to identify (highlight) types that are defined in the current file / project within a given namespace as opposed to the types defined in other files / projects (within identically named namespace). I have some files that contain multiple types within the same namespace, and it would be nice to see which of those types are defined in the current file without scrolling the code - just by looking at the NaviBar's namespace dropdown.

In fact maybe this can be generalized to the following filter modes:

• Current file only
• Current project
• Current project + all projects it depends on
• Entire solution

Perhaps with an option to remember these settings for a given namespace?
This will also address the performance concerns, as the default could be current project only for example.

2. I seem to get inconsistent results with the number of items being listed for namespace dropdowns. Eventually I seem to get all members (after having dropped down the Namespace item several times from different files and projects). I understand that it takes time for this info to be gathered and computed. So the suggestion would be to show some kind of indication - an icon, label, progress bar that informs the user that the items are still being gathered. This is similar to how VS Intellisense does it when it is trying to display large number of Intellisense items.

Start by locating the NaviBar namespace dropdown implementation and review how its listed types and loading state are gathered. Compare the requested current-file/project/solution filters and progress indication with the existing behavior; done means the selected scope is reflected in the dropdown and users can tell when items are still being gathered.