Re-name and re-factor the PDFLinkService.navigateTo method

This modernizes and improves the code, by using `async`/`await` and by extracting the helper function to its own method.
To hopefully avoid confusion, given the next patch, the method is also re-named to `goToDestination` to make is slightly clearer what it actually does.

web/pdf_outline_viewer.js

@@ -73,7 +73,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
     element.href = linkService.getDestinationHash(dest);
     element.onclick = () => {
       if (dest) {
-        linkService.navigateTo(dest);
+        linkService.goToDestination(dest);
       }
       return false;
     };