pgsql: Use streaming read I/O in heap amcheck

Use streaming read I/O in heap amcheck

Instead of directly invoking ReadBuffer() for each unskippable block in
the heap relation, verify_heapam() now uses the read stream API to
acquire the next buffer to check for corruption.

Author: Matheus Alcantara <matheusssilv97(at)gmail(dot)com>
Co-authored-by: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Reviewed-by: Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
Reviewed-by: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Reviewed-by: jian he <jian(dot)universality(at)gmail(dot)com>
Discussion: https://postgr.es/m/flat/CAFY6G8eLyz7%2BsccegZYFj%3D5tAUR-GZ9uEq4Ch5gvwKqUwb_hCA%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/043799fa08c2c71f35816ca067951266d2e9ebe0

Modified Files
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contrib/amcheck/verify_heapam.c | 133 +++++++++++++++++++++++++++++++--------
src/tools/pgindent/typedefs.list | 1 +
2 files changed, 109 insertions(+), 25 deletions(-)