pgsql: Add command column to pg_stat_progress_create_index

Add command column to pg_stat_progress_create_index

This allows determining which command is running, similar to
pg_stat_progress_cluster.

Discussion: https://www.postgresql.org/message-id/flat/f0e56b3b-74b7-6cbc-e207-a5ed6bee18dc%402ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c880096dc1e14b62610aa34bc98db226fa134260

Modified Files
--------------
doc/src/sgml/monitoring.sgml         | 11 ++++++++++-
src/backend/catalog/index.c          |  2 ++
src/backend/catalog/system_views.sql |  5 +++++
src/backend/commands/indexcmds.c     |  8 ++++++++
src/include/catalog/catversion.h     |  2 +-
src/include/commands/progress.h      |  7 +++++++
src/test/regress/expected/rules.out  |  7 +++++++
7 files changed, 40 insertions(+), 2 deletions(-)