DPL Analysis: add pack selector functions

[aalkin]

[alibuild]

Error while checking build/O2/fullCI for 12d3c61a833af6eeef3bca58c7e9d4b7789da923 at 2024-09-08 20:28:

## sw/BUILD/O2-latest/log
c++: error: unrecognized command-line option '--rtlib=compiler-rt'
c++: error: unrecognized command-line option '--rtlib=compiler-rt'


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
/sw/SOURCES/O2/12679-slc8_x86-64/0/EventVisualisation/Workflow/src/EveWorkflowHelper.cxx:898:16: error: 'signed char' to 'int' conversion; consider casting to 'unsigned char' first. [bugprone-signed-char-misuse]
/sw/SOURCES/O2/12679-slc8_x86-64/0/EventVisualisation/Workflow/src/EveWorkflowHelper.cxx:898:16: error: 'signed char' to 'int' conversion; consider casting to 'unsigned char' first. [bugprone-signed-char-misuse]
++ [[ 0 == 0 ]]
++ exit 1
--

Full log here.