R1:c37b6c663397

When users click a symbol in Differential to jump to the definition, include path/line context

Summary:
Ref T13047. In some reasonable cases, knowing the path and line number where a symbol appears is useful in ranking or filtering the set of matching symbols.

Giving symbol sources more information can't hurt, and it's generally free for us to include this context since we just need to grab it out of the document and pass it along.

We can't always get this data (for example, if a user types `s idx` into…