[PWGUD] Adding new task to study vector meson production per ROF

[rolavick]

• also making few partial fixes to other UD code

[github-actions]

O2 linter results: ❌ 1 errors, ⚠️ 0 warnings, 🔕 0 disabled

[alibuild]

Auto-approving on behalf of @rolavick.

[alibuild]

Error while checking build/O2Physics/o2 for a14ff2e at 2026-06-20 13:31:

## sw/BUILD/O2Physics-latest/log
CMake Error at cmake/O2PhysicsAddExecutable.cmake:113 (add_executable):
CMake Error at cmake/O2PhysicsAddExecutable.cmake:113 (add_executable):
ninja: error: rebuilding 'build.ninja': subcommand failed

Full log here.