pgsql: Add function to pump IPC process until string match

Add function to pump IPC process until string match

Refactor the recovery tests to not carry a local duplicated copy of
the pump_until function which pumps a process until a defined string
is seen on a stream. This reduces duplication, and is in preparation
for another patch which will also use this functionality.

Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Discussion https://postgr.es/m/YgynUafCyIu3jIhC@paquier.xyz

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/6da65a3f9a9deae4fdcc768c612b0c8f52759f75

Modified Files
--------------
src/test/perl/PostgreSQL/Test/Utils.pm | 23 +++++++++++++++
src/test/recovery/t/013_crash_restart.pl | 46 +++++++----------------------
src/test/recovery/t/022_crash_temp_files.pl | 45 +++++-----------------------
3 files changed, 41 insertions(+), 73 deletions(-)