Providing an box generator natively for ALICEO2.

[sawenzel]

This is useful for:

• testing (building gap and cocktail generators)
• better status code propagation

[github-actions]

REQUEST FOR PRODUCTION RELEASES:
To request your PR to be included in production software, please add the corresponding labels called "async-" to your PR. Add the labels directly (if you have the permissions) or add a comment of the form (note that labels are separated by a ",")

+async-label <label1>, <label2>, !<label3> ...

This will add <label1> and <label2> and removes <label3>.

The following labels are available
async-2023-pbpb-apass
async-2023-pp-apass1
async-2022-pp-apass6
async-2022-pp-apass4
async-mc
async-data

[alibuild]

Error while checking build/O2/fullCI for 2325014 at 2024-04-03 16:51:

## 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/O2/12980-slc8_x86-64/0/Generators/src/BoxGenerator.cxx:48:24: error: statement should be inside braces [readability-braces-around-statements]
++ [[ 0 == 0 ]]
++ exit 1
--

Full log here.