pgsql: Add additional information in the vacuum error context.

Add additional information in the vacuum error context.

The additional information added will be an offset number for heap
operations. This information will help us in finding the exact tuple due
to which the error has occurred.

Author: Mahendra Singh Thalor and Amit Kapila
Reviewed-by: Sawada Masahiko, Justin Pryzby and Amit Kapila
Discussion: https://postgr.es/m/CAKYtNApK488TDF4bMbw+1QH8HJf9cxdNDXquhU50TK5iv_FtCQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7e453634bb62f06a048f5562ba59d52aa1f28d12

Modified Files
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src/backend/access/heap/pruneheap.c  | 19 +++++++-
src/backend/access/heap/vacuumlazy.c | 91 ++++++++++++++++++++++++++++--------
src/include/access/heapam.h          |  3 +-
3 files changed, 90 insertions(+), 23 deletions(-)