[PWGUD] Introduce minimalistic UPC candidate producer for central barrel

[nburmaso]

No description provided.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 5 disabled

[alibuild]

Error while checking build/O2Physics/code-check for 31ee60f at 2026-09-10 21:13:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 16 errors and 1 warnings.'
Found 16 errors and 1 warnings.
++ [[ 16 -gt 0 ]]
++ cat /sw/BUILD/ababc2a879c2de2996a1b4ca14c35471593d4716/O2Physics-code-check/errors.txt
PWGUD/TableProducer/upcCandProducerBarrel.cxx:116:1: error: no header providing "DECLARE_SOA_COLUMN" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:145:1: error: no header providing "DECLARE_SOA_TABLE" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:174:3: error: no header providing "o2::framework::Produces" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:176:3: error: no header providing "o2::framework::Service" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:196:35: error: no header providing "o2::soa::Join" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:196:45: error: no header providing "o2::aod::Collisions" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:197:38: error: no header providing "o2::aod::BCsWithTimestamps" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:198:40: error: no header providing "o2::aod::Tracks" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:198:53: error: no header providing "o2::aod::TracksExtra" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:201:3: error: no header providing "o2::framework::Preslice" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:201:60: error: no header providing "o2::aod::track::collisionId" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:216:57: error: no header providing "o2::framework::HistType" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:248:112: error: no header providing "o2::aod::FT0s" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:248:135: error: no header providing "o2::aod::FV0As" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:248:159: error: no header providing "o2::aod::FDDs" is directly included [misc-include-cleaner,-warnings-as-errors]
PWGUD/TableProducer/upcCandProducerBarrel.cxx:282:40: error: no header providing "TESTBIT" is directly included [misc-include-cleaner,-warnings-as-errors]
++ [[ 1 -gt 0 ]]
++ cat /sw/BUILD/ababc2a879c2de2996a1b4ca14c35471593d4716/O2Physics-code-check/warnings.txt
PWGUD/TableProducer/upcCandProducerBarrel.cxx:173:8: warning: constructor does not initialize these fields: ccdb [cppcoreguidelines-pro-type-member-init]
++ [[ 16 -gt 0 ]]
++ exit 1
--

Full log here.