Fix pg_amcheck --skip option parameter handling
The skip options set for all-visible and all-frozen were incorrect
as they used space rather than hyphen, causing a syntax error when
invoked. Also, the option for not skipping any pages at all, none,
was documented but not implemented.
Backpatch through 14 where pg_amcheck was introduced.
Bug: #17149
Reported-by: Chen Jiaoqian <chenjq.jy@fujitsu.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/17149-
5918ea748da36b15@postgresql.org
Backpatch-through: 14