ProblemNavigationContext: Fix incorrect link target for file:line links with declarations

For certain "file:line" links displayed for problems in the context browser, clicking the link switched the context browser to the associated declaration instead of jumping to the line in the code. This is the same action as on clicking the declaration link displayed before the file:line link. This seems like a bug, since file:line links should probably always jump to the line instead of doing something else. This merge request fixes that issue.

For reproducing the issue, you'll need a problem widget that looks like this:

I marked the file:line links in green and red. The green ones already behaved correctly before this merge request. The red ones only behave correctly after applying this merge request. Otherwise, they perform the same action as clicking the other link in the same line before them.