Add CLI Exec in SQL.

[SeinoYuki]

Hi,

I'm working to support CLI executer in SQL.

This is accomplished with a function.
Nothing special.
Just return the result of the pg_statsinfo command as a record.

An example is as follows.

postgres=# select statsinfo.cli_exec('-r All -h localhost -d postgres -p 5432 -U postgres');
                                                                                                                cli_exec                                                                                                                
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 ---------------------------------------------                                                                                                                                                                                         +
 STATSINFO Report (host: host01, port: 5432)                                                                                                                                                                                     +
 ---------------------------------------------                                                                                                                                                                                         +
                                                                                                                                                                                                                                       +
 ----------------------------------------                                                                                                                                                                                              +
 /* Summary */                                                                                                                                                                                                                         +
 ----------------------------------------                                                                                                                                                                                              +
 Database System ID   : 7199845336452441890                                                                                                                                                                                            +
 Host                 : host01                                                                                                                                                                                                   +
 Port                 : 5432                                                                                                                                                                                                           +
 PostgreSQL Version   : 14.7                                                                                                                                                                                                           +
 Snapshot Begin       : 2023-02-14 12:19:50                                                                                                                                                                                            +
 Snapshot End         : 2023-02-14 12:20:00                                                                                                                                                                                            +
 Snapshot Duration    : 00:00:10                                                                                                                                                                                                       +
 Total Database Size  : 10 MiB                                                                                                                                                                                                         +
 Total Commits        : 999                                                                                                                                                                                                            +
 Total Rollbacks      : 0                                                                                                                                                                                                              +
                                                                                                                                                                                                                                       +
 /** Alert **/                                                                                                                                                                                                                         +
~~~

Regards,