Hierarchical Chunker TripletTableSerializer joins table rows into one massive block

### Bug
Given a table

| column_a | column_b | column_c |
|--|--|--|
| a | b | c |
| d | e | f |

The TripletTableSerializer turns it into
```
a, column_b = b. column_c = c. d, column_b = e. column_c = f.
```

Ideally the columns would be separated by commas and the rows would be on different lines or at least using a different separator