Custom reloptions for table AM

Custom reloptions for table AM

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

The reloptions, which could be used outside of table AM, are now extracted
into the CommonRdOptions data structure.  These options could be by decision
of table AM directly specified by a user or calculated in some way.

The new test module test_tam_options evaluates the ability to set up custom
reloptions and calculate fields of CommonRdOptions on their base.

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, Jess Davis