migrate stuff from physics benchmarks to detector benchmarks (#63)

.gitlab-ci.yml

Snakefile

benchmarks/insert_neutron/Snakefile

benchmarks/insert_neutron/analysis/gen_particles.cxx

benchmarks/insert_neutron/analysis/neutron_plots.py

benchmarks/insert_neutron/config.yml

benchmarks/zdc_lambda/Snakefile

benchmarks/zdc_lambda/analysis/gen_lambda_decay.cxx

benchmarks/zdc_lambda/analysis/lambda_plots.py

benchmarks/zdc_lambda/config.yml

benchmarks/zdc_sigma/Snakefile

benchmarks/zdc_sigma/analysis/gen_sigma_decay.cxx

benchmarks/zdc_sigma/analysis/sigma_plots.py

benchmarks/zdc_sigma/config.yml