Bytecode version diff should use a different rendering

Today we're using a common diff helper, but it doesn't serve the content well.

```
BYTECODE VERSIONS:

old │ new │ diff
─────┼─────┼───────────
1 │ 1 │ 0 (+1 -1)

+ org.example.MainKt: 65

- org.example.MainKt: 69
```

It should probably be something like

```
BYTECODE VERSIONS:

version │ old │ new │ diff
─────────┼─────┼───────────
65 │ 256 │ 255 │ -1 (0 -1)
69 │ 0 │ 1 │ +1 (+1 0)

org.example.MainKt: 65 → 69
```

Not sure whether we should show new types and their versions here. Maybe we combine with the types output?

Start by locating the bytecode version output and the common diff helper used to render it. Update the rendering to present version, old, new, and diff columns with the class version transition, and resolve whether new types and their versions belong in this output or the types output.

Written by the indexing model from the issue text.