pgsql: Add a script and a config file to run perlcritic

Add a script and a config file to run perlcritic

This is similar to what we do to run perltidy. For now we only run at
severity level 5. Over time we can improve our perl code and reduce the
severity level.

Discussion: https://postgr.es/m/86aa2a3a-0c68-21fb-9560-84ad6914d561@2ndQuadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/91703ca2144e58d041c132fb7ff06a6d1721e904

Modified Files
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src/tools/pgperlcritic/perlcriticrc | 14 ++++++++++++++
src/tools/pgperlcritic/pgperlcritic | 28 ++++++++++++++++++++++++++++
2 files changed, 42 insertions(+)