Support Show commands in stored procedures and funcitons

Users write SP and UDFs to generate test data and as part of in-house written deployment tools e.g. when creating schema objects, they update the version of the schema and need information from the CRDB cluster in order to follow a certain path. For this purpose SHOW commands are need to be used. But today, SHOW commands are not supported in SPs and UDFs

Add support to allow SHOW commands in stored procedures functions

Jira issue: CRDB-65641

Epic: CRDB-65937

Search the repository for stored-procedure and UDF statement handling, then trace how SHOW commands are parsed and executed. Confirm the supported SHOW commands can run inside both stored procedures and functions, including the data needed by deployment tools, and add or update focused coverage where the existing behavior is tested.

Written by the indexing model from the issue text.