Linter: Provide autofix for conditionals in `erb-no-interpolated-class-names` rule

We should provide an autofix if the interpolation has static string leaf nodes:

```erb
<figure class="attachment attachment--<%= blob.representable? ? "preview" : "file" %>"></figure>
```

should be fixed to
```erb
<figure class="attachment <% if blob.representable? %> attachment--preview <% else %> attachment--file <% end %>"></figure>
```

