Report wait events for local shell commands like archive_command.
This commit introduces new wait events for archive_command,
archive_cleanup_command, restore_command and recovery_end_command.
Author: Fujii Masao
Reviewed-by: Bharath Rupireddy, Michael Paquier
Discussion: https://postgr.es/m/
4ca4f920-6b48-638d-08b2-
93598356f5d3@oss.nttdata.com