@wip-new-core, fix the pretty formatter scenarios in the outlines.feature

To fix the pretty formatter scenarios in the outlines.feature the following two changes are needed:
  -- Use the outline step name in the error backtrace, instead of the instantiated step name (requires cucumber/cucumber-ruby-core#60).
  -- Do not call formatter.exception for outline failures in the legacy_formatter (as inconsistent as it might seem, this is the behaviour in v1.3.x)

The one scenario in outlines.feature that after this PR is still tagged ```@wip-new-core```, has a diff in the progress formatter output:
```
 - "--U-..F-.."
 + "------..FF--.."
```

This PR is built on top of #713