pgsql: vacuumdb: Add option for analyzing only relations missing stats.

vacuumdb: Add option for analyzing only relations missing stats.

This commit adds a new --missing-stats-only option that can be used
with --analyze-only or --analyze-in-stages.  When this option is
specified, vacuumdb will analyze a relation if it lacks any
statistics for a column, expression index, or extended statistics
object.  This new option is primarily intended for use after
pg_upgrade (since it can now retain most optimizer statistics), but
it might be useful in other situations, too.

Author: Corey Huinker <corey.huinker@gmail.com>
Co-authored-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Discussion: https://postgr.es/m/Z5O1bpcwDrMgyrYy%40nathan

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/edba754f052ea0c02287080004aa6051eaa4f597

Modified Files
--------------
doc/src/sgml/ref/vacuumdb.sgml           |  16 +++++
src/bin/scripts/t/100_vacuumdb.pl        |  60 ++++++++++++++++
src/bin/scripts/vacuumdb.c               | 114 ++++++++++++++++++++++++++++++-
src/test/perl/PostgreSQL/Test/Cluster.pm |  27 ++++++++
4 files changed, 215 insertions(+), 2 deletions(-)