Add baseline metrics for remaining execution plan nodes

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

We want basic understanding of where a plan's time is spent and in what operators. See #866 for more details

This information has been added (#866) for intermediate operators but not for low level readers for parquet, json, csv, and avro.

Describe the solution you'd like
Add "baseline" metrics (start time, stop time, output rows, and elapsed_compute) for the data source ExecutionPlans:

1. ParquetExec
2. NdJsonExec
3. NdJsonExec
4. AvroExec
5. CsvExec
6. CrossJoinExec
7. EmptyExec
8. MemoryExec

Describe alternatives you've considered
None

Additional context
It should be straightforward to follow the model for adding statistics on the following PRs:

• Add metrics for Limit and Projection, and CoalesceBatches #1004
• Add metrics for FilterExec #960

[Dandandan]

What about CsvExec, CrossJoinExec, EmptyExec, MemoryExec?

[alamb]

Good eyes @Dandandan -- including them in the description

[alamb]

I don't plan any more work on this ticket -- we can add metrics to other operators if there is a specific need