pgsql: Custom reloptions for table AM

Custom reloptions for table AM

Let table AM define custom reloptions for its tables.  This allows to
specify AM-specific parameters by WITH clause when creating a table.

The code may use some parts from prior work by Hao Wu.

Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Discussion: https://postgr.es/m/AMUA1wBBBxfc3tKRLLdU64rb.1.1683276279979.Hmail.wuhao%40hashdata.cn
Reviewed-by: Reviewed-by: Pavel Borisov, Matthias van de Meent

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c95c25f9af4bc77f2f66a587735c50da08c12b37

Modified Files
--------------
src/backend/access/common/reloptions.c   |  6 ++--
src/backend/access/heap/heapam_handler.c | 12 +++++++
src/backend/access/table/tableamapi.c    | 25 +++++++++++++++
src/backend/commands/tablecmds.c         | 55 +++++++++++++++++++-------------
src/backend/postmaster/autovacuum.c      |  4 ++-
src/backend/utils/cache/relcache.c       |  6 +++-
src/include/access/reloptions.h          |  2 ++
src/include/access/tableam.h             | 43 +++++++++++++++++++++++++
8 files changed, 126 insertions(+), 27 deletions(-)