pgsql: Provide a way block-level table AMs could re-use acquire_sample_

Provide a way block-level table AMs could re-use acquire_sample_rows()

While keeping API the same, this commit provides a way for block-level table
AMs to re-use existing acquire_sample_rows() by providing custom callbacks
for getting the next block and the next tuple.

Reported-by: Andres Freund
Discussion: https://postgr.es/m/20240407214001.jgpg5q3yv33ve6y3%40awork3.anarazel.de
Reviewed-by: Pavel Borisov

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dd1f6b0c172a643a73d6b71259fa2d10378b39eb

Modified Files
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src/backend/access/heap/heapam_handler.c | 12 +++++++
src/backend/commands/analyze.c           | 42 +++++++++++++++---------
src/include/access/tableam.h             | 13 ++++++++
src/include/commands/vacuum.h            | 56 ++++++++++++++++++++++++++++++--
src/tools/pgindent/typedefs.list         |  2 ++
5 files changed, 106 insertions(+), 19 deletions(-)