<!-- The PR description should answer 2 important questions: -->

### What

- Adds datafusion row metrics to our NDC query and aggregate nodes, for
explain output
- Aggregates all datafusion metrics in the trace attributes:
- `rows_processed`, i.e. total number of rows considered over all
execution plan nodes
- `elapsed_compute`, i.e. CPU time spent in _processing_ data (not
fetching it)
- Adds the explain output to the `create_logical_plan` span.

E.g. a query we don't push down to NDC:

```sql
SELECT
    COUNT(42 * invoiceId) AS odd_count
FROM
    InvoiceLine;
```

Attributes:

```text
rows_processed: 2242
total_rows: 1
elapsed_compute: 417
logical_plan: Projection: count(Int64(42) * InvoiceLine.invoiceId) AS odd_count
  Aggregate: groupBy=[[]], aggr=[[count(Int64(42) * InvoiceLine.invoiceId)]]
    TableScan: InvoiceLine
```

The metrics clearly indicate that the cost in terms of rows processed
per row returned (2242 / 1) is very high in this case. The logical plan
makes it clear why this was the case: we failed to push down the
aggregate node.

### How

<!-- How is it trying to accomplish it (what are the implementation
steps)? -->

V3_GIT_ORIGIN_REV_ID: c26cce9adab9d0feb0a7d2873a3eea38542564a0