UI/interaction issues still present in Document Outline.

[CyrusNajmabadi]

Even with #65641 "Document Outline" still needs more work done to be a reasonable production-ready feature.

Issues include:

• Sort buttons do not show their state, making it unclear what the current sorting state is #68096
  
• Sort state is not preserved across VS sessions. #68100
• SearchBar lacks history, as well as normal x adornment to clear the search #68098
  
• As you navigate in a file, the selected item in the view will be updated, but will not scroll into view. So finding that item is extremely challenging (in large files). #68102
• the tree-view resets to the top whenever the model is updated, making is so you lose your place in the tree. #68103

Overall, the experience feels unpolished and not scaled up to meet the needs of large files. UI/bg behavior is fine. But it needs much more work to be production-ready.

[sharwell]

@CyrusNajmabadi I believe that items (2) and (3) could be reasonably deferred, depending on complexity

For item (2), persisting a new global option should not be particularly difficult. We do this for many other options today.
For item (3), we should investigate if the Test Explorer search box is part of the shared platform UI, and if so use that.