Multi-line merge request comments: 4. Add line-span information to comments on the Overview tab

The following discussion from !29516 (merged) should be addressed:

• @pedroms started a discussion: (+1 comment)

  @jboyson 🤔 Question: Is showing the full commented range in the “Overview” tab a follow-up to this MR? Or is it feasible to include here? As shown in the example image below, the comment range extends beyond the lines being shown in that “preview” of the changes.

  

Note: This should also bring the highlight to the respective lines.