arrow

ARROW-9889: [Rust][DataFusion] Implement physical plan for EmptyRelation

This fixes an error I saw in the Datafusion CLI. Running `CREATE EXTERNAL TABLE` errors with `"Unsupported logical plan variant"`

Before this PR, you can't make an external table via the CLI:

```
>    create external table test(c1 boolean) stored as CSV location '/tmp/foo';
General("Unsupported logical plan variant")
>
```
After this PR:

```
> create external table test(c1 boolean) stored as CSV location '/tmp/foo';
0 rows in set. Query took 0 seconds.
>
```

Other changes:
* Made the list of unsupported plan nodes explicit in the planer
* Added a test for this behavior.

I think this error was introduced in https://github.com/apache/arrow/pull/8027 which started (rightly) to treat all execution plans in a uniform way and do less special casing. FYI @andygrove

Closes #8083 from alamb/alamb/ARROW-9889-create-table

Authored-by: alamb <andrew@nerdnetworks.org>
Signed-off-by: Andy Grove <andygrove73@gmail.com>