Show runtime config #18452
Description
Is your feature request related to a problem or challenge?
SHOW cannot display runtime settings such as datafusion.runtime.memory_limit.
> SHOW datafusion.runtime.memory_limit;
Error during planning: 'datafusion.runtime.memory_limit' is not a variable which can be viewed with 'SHOW'
Describe the solution you'd like
I would like SHOW to support querying runtime settings, similar to how it works for other configuration variables. For example:
> SHOW datafusion.runtime.memory_limit;
+-----------------------------------------------+
| name | value |
+-----------------------------------------------+
| datafusion.runtime.memory_limit | 1073741824 |
+------------------------------------------------+
Describe alternatives you've considered
No response
Additional context
No response