Show banner or current selection when raw stack trace is selected

### Problem Statement

It is easy to forget that raw stack trace was selected, and can make it appear as if symbolication is not working.

### Solution Brainstorm

Showing some sort of banner or the current selection in the UI could make this clearer.

### Product Area

Issues

Start in the Issues product area by reproducing the state where raw stack trace is selected and symbolication appears inactive. Compare the current selection and banner behavior in that UI, then define completion as making the selected raw-stack-trace state visibly clear without disrupting symbolication.

Written by the indexing model from the issue text.