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ARROW-12106: [Rust][DataFusion] Support `SELECT * from information_schema.tables`

# Rationale
Provide configurable access to a table list so a user can see what tables exist).

See the doc for background: https://docs.google.com/document/d/12cpZUSNPqVH9Z0BBx6O8REu7TFqL-NPPAYCUPpDls1k/edit#

I plan to add support for `SHOW TABLES` (and `information_schema.columns` / `SHOW COLUMNS`) as follow on PRs

# Example use:

Setup:
```
echo "1" > /tmp/table.csv
echo "2" >> /tmp/table.csv
cargo run --bin datafusion-cli
```

Then run :

```
>  CREATE EXTERNAL TABLE t(a int)
STORED AS CSV
LOCATION '/tmp/table.csv';

0 rows in set. Query took 0 seconds.
> select * from information_schema.tables;

+---------------+--------------------+------------+--------------+
| table_catalog | table_schema       | table_name | table_type   |
+---------------+--------------------+------------+--------------+
| datafusion    | public             | t          | BASE TABLE   |
| datafusion    | information_schema | TABLES     | SYSTEM TABLE |
+---------------+--------------------+------------+--------------+
2 row in set. Query took 0 seconds.
z>
```

Closes #9818 from alamb/alamb/show_tables

Authored-by: Andrew Lamb <andrew@nerdnetworks.org>
Signed-off-by: Andrew Lamb <andrew@nerdnetworks.org>