Consistently order and differentiate navto results

[amcasey]

In some circumstances, it is possible to have both an input and output file present in open projects at the same time. The motivating example was in VS when a TS file is open in one editor tab and a cshtml file consuming the corresponding JS file via <script src= is open in another (VS rewrites the <script src= to a triple-slash reference before sending the text to the server). In this scenario, the TS file is open in a configured project and the JS file is closed, but present, in an inferred project. (This particular scenario does not affect VS Code, which does not rewrite <script src=, but you can just open both files.)

When navigate-to (protocol request navto[-full]), aka go-to-symbol, is invoked, it shows declarations from both the TS and the JS files. While it's possible they could be de-dup'd through some amount of source-mapping or other relationship tracking, that is likely to be prohibitively expensive for the number of entries involved in a typical navto response.

Instead, we should just ensure that the elements are returned in a predictable order (e.g. always prefer TS) and, ideally, provide enough information to differentiate them (presently, they both get the same icon, indicating only the type of symbol).

[andrewbranch]

Relevant points also mentioned in the discussion:

• Fuzzy search might mess with the order as you type? (Hopefully not if both items have identical text)
• Might we migrate to letting AnyCode handle NavTo?