Optionally store refs on ITS parts of all PV contributors

[shahor02]

To allow accessing them w/o going throught all kinds of tracks

[alibuild]

Error while checking build/O2/fullCI_slc9 for 3756001 at 2026-05-31 22:00:

## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/Detectors/GlobalTracking/src/MatchCosmics.cxx:594:31: error: statement should be inside braces [readability-braces-around-statements]
++ [[ 0 == 0 ]]
++ exit 1
--

Full log here.