Add find_in_log() and advance_wal() perl functions to core test framework (?)

Hi,

It seems like find_in_log() and advance_wal() functions (which are now
being used in at least 2 places). find_in_log() is defined and being
used in 2 places 019_replslot_limit.pl and 033_replay_tsp_drops.pl.
The functionality of advancing WAL is implemented in
019_replslot_limit.pl with advance_wal() and 001_stream_repl.pl with
the same logic as advance_wal() but no function there and an
in-progress feature [1] needs advance_wal() as-is for tests.

Do these functions qualify to be added to the core test framework in
Cluster.pm? Or do we need more usages of these functions before we
generalize and add to the core test framework? If added, a bit of
duplicate code can be reduced and they become more usable across the
entire tests for future use.

Thoughts?

[1] https://www.postgresql.org/message-id/CALj2ACUYz1z6QPduGn5gguCkfd-ko44j4hKcOMtp6fzv9xEWgw@mail.gmail.com

--
Bharath Rupireddy
RDS Open Source Databases: https://aws.amazon.com/rds/postgresql/