pgsql: Add pg_dissect_walfile_name()

Add pg_dissect_walfile_name()

This function takes in input a WAL segment name and returns a tuple made
of the segment sequence number (dependent on the WAL segment size of the
cluster) and its timeline, as of a thin SQL wrapper around the existing
XLogFromFileName().

This function has multiple usages, like being able to compile a LSN from
a file name and an offset, or finding the timeline of a segment without
having to do to some maths based on the first eight characters of the
segment.

Bump catalog version.

Author: Bharath Rupireddy
Reviewed-by: Nathan Bossart, Kyotaro Horiguchi, Maxim Orlov, Michael
Paquier
Discussion: https://postgr.es/m/CALj2ACWV=FCddsxcGbVOA=cvPyMr75YCFbSQT6g4KDj=gcJK4g@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cca186348929cd75f23ef1b25922386bf38cf99c

Modified Files
--------------
doc/src/sgml/func.sgml | 33 +++++++++++++++++
src/backend/access/transam/xlogfuncs.c | 53 ++++++++++++++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 7 ++++
src/test/regress/expected/misc_functions.out | 23 ++++++++++++
src/test/regress/sql/misc_functions.sql | 8 +++++
6 files changed, 125 insertions(+), 1 deletion(-)