Add TAP test for archive_cleanup_command and recovery_end_command

Add TAP test for archive_cleanup_command and recovery_end_command

This adds tests checking for the execution of both commands.  The
recovery test 002_archiving.pl is nicely adapted to that, as promotion
is triggered already twice there, and even if any of those commands fail
they don't affect recovery or promotion.

A command success is checked using a file generated by an "echo"
command, that should be able to work in all the buildfarm environments,
even Msys (but we'll know soon about that).  Command failure is tested
with an "echo" command that points to a path that does not exist,
scanning the backend logs to make sure that the failure happens.  Both
rely on the backend triggering the commands from the root of the data
folder, making its logic more robust.

Thanks to Neha Sharma for the extra tests on Windows.

Author: Amul Sul, Michael Paquier
Reviewed-by: Andres Freund, Euler Taveira
Discussion: https://postgr.es/m/CAAJ_b95R_c4T5moq30qsybSU=eDzDHm=4SPiAWaiMWc2OW7=1Q@mail.gmail.com