* Refactor FileDialogTreeBuilder to be more generally useful outside of dialog context
* Fix comparer
* Change TreeViewFileSystem scenario to use the core builder
* Refactor icon provision for reusability
* Add IsOpenGetter implementations
* Xmldoc and tests
* xmldoc and trim icon when blank (files and no nerd)
* unit test fixes
* FixFix unit tests when running on linux
* Add option to pick which icon set to use for TreeViewFileSystem
* Add spaces when using nerd to avoid icon overaps
* Refactor the addition of space for nerd icons to reduce code duplication
