ITS3: alignment code

[f3sch]

This removes entirely the previous misalignment code (that's why the digitiser is touched), adds the possibility to study different mis-alignment modes and its effect on the residuals and implements a more or less finished prototype to interface with GBL&MillePede to find back the injected mis-alignment.

[github-actions]

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[alibuild]

Error while checking build/O2/fullCI_slc9 for ec29880 at 2026-03-15 21:15:

## sw/BUILD/O2-latest/log
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.

Full log here.

[f3sch]

needs something like #15162

[alibuild]

Error while checking build/O2/fullCI_slc9 for a3b972a at 2026-03-25 22:10:

## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
/sw/SOURCES/O2/15161-slc9_x86-64/0/Detectors/Upgrades/ITS3/alignment/src/AlignmentHierarchy.cxx:19:10: error: inclusion of deprecated C++ header 'math.h'; consider using 'cmath' instead [modernize-deprecated-headers]
++ [[ 0 == 0 ]]
++ exit 1
--

Full log here.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 7c07166 at 2026-03-26 18:16:

## sw/BUILD/o2codechecker-latest/log
100% tests passed, 0 tests failed out of 1


## sw/BUILD/O2Physics-latest/log
c++: fatal error: Killed signal terminated program cc1plus
c++: fatal error: Killed signal terminated program cc1plus
ninja: build stopped: subcommand failed.

Full log here.