WIP: Visually align expected and actual values
Patch for #17702 (closed).
A couple notes:
- Some "test driver" files in the test suite, such as
primops/should_run/ArithInt8.hs, have similar actual/expected messages, so I updated those as well. - I updated coreSyn/CoreLint.hs even though the offending message didn't appear in any test cases found by searching the GitLab project for
Expected:.