Add a field disk usage API

[romseygeek]

Problem Statement

Related to #10370, it would be useful to have an idea of how much disk space is used by different table columns - in particular this will be helpful to people who are using DROP COLUMN to save disk.

Generating this information can end up being quite expensive so it may be worth adding it as an option to ANALYZE to run in the background.

Possible Solutions

cr> select * from sys.disk_usage where table_name=my_table;
+--------+------------+-------+----------------+-------+
| schema | table_name | field | data_structure | bytes |
+--------+------------+-------+----------------+-------+
| doc    | my_table   | name | index           | 65065 |
| doc    | my_table   | name | doc_values      | 25122 |
...

Considered Alternatives

No response