Add cost-based vacuum delay time to progress views.

Add cost-based vacuum delay time to progress views.

This commit adds the amount of time spent sleeping due to
cost-based delay to the pg_stat_progress_vacuum and
pg_stat_progress_analyze system views.  A new configuration
parameter named track_cost_delay_timing, which is off by default,
controls whether this information is gathered.  For vacuum, the
reported value includes the sleep time of any associated parallel
workers.  However, parallel workers only report their sleep time
once per second to avoid overloading the leader process.

Bumps catversion.

Author: Bertrand Drouvot 
Co-authored-by: Nathan Bossart 
Reviewed-by: Sami Imseih 
Reviewed-by: Robert Haas 
Reviewed-by: Masahiko Sawada 
Reviewed-by: Masahiro Ikeda 
Reviewed-by: Dilip Kumar 
Reviewed-by: Sergei Kornilov 
Discussion: https://postgr.es/m/ZmaXmWDL829fzAVX%40ip-10-97-1-34.eu-west-3.compute.internal