pgsql: For PostgreSQL::Test compatibility, alias entire package symbol

For PostgreSQL::Test compatibility, alias entire package symbol tables.

Remove the need to edit back-branch-specific code sites when
back-patching the addition of a PostgreSQL::Test::Utils symbol. Replace
per-symbol, incomplete alias lists. Give old and new package names the
same EXPORT and EXPORT_OK semantics. Back-patch to v10 (all supported
versions).

Reviewed by Andrew Dunstan.

Discussion: https://postgr.es/m/20220622072144.GD4167527@rfd.leadboat.com

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/e8f037a2df9b6f5936c7958dcc18a2b8d609f410

Modified Files
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src/test/perl/PostgreSQL/Test/Cluster.pm | 9 ++++---
src/test/perl/PostgreSQL/Test/Utils.pm | 38 ++++--------------------------
src/test/perl/PostgresNode.pm | 25 +++++++++-----------
src/test/perl/TestLib.pm | 40 --------------------------------
4 files changed, 21 insertions(+), 91 deletions(-)