Add online unpacking par files for MUCH (+ folder for mCBM May 2025)

Of Interest to @v.singhal @c.ghosh_AT_vecc.gov.in

Replaces the hard-coded implementation in the online unpacker

1. Yaml files corresponding to original parameters for
   • 2022-2024 (top folder one) (online/readoutPar/mcbm2024_05/ + symbolic link in online/recoPar/mcbm_beam_2024_05_08_nickel/)
   • February-March 2025 (2025_02 sub-folder) (online/readoutPar/mcbm2025_02/ + symbolic links in
     online/recoPar/mcbm_beam_2025_02_14_silver_3505/
online/recoPar/mcbm_beam_2025_02_14_silver_3531/
online/recoPar/mcbm_beam_2025_02_14_silver_3570/
online/recoPar/mcbm_beam_2025_02_14_silver_3603/ \
   • May 2025 with GEMs type 1 and 2 (2025_05 sub-folder) (online/readoutPar/mcbm2025_05/ + symbolic link in online/recoPar/mcbm_beam_2025_05_iron_bistmuth/)
2. Changes to the corresponding MainConfig.yaml in 5 existing online/recoPar/ sub-folders
3. New folder online/recoPar/mcbm_beam_2025_05_iron_bistmuth/ with symbolic links to online/recoPar/mcbm_beam_2025_02_14_silver_3603/ for all other readout and reco parameter files

Corresponding MR on source code side still pending as of creation of this MR, description will be updated when it is created
Corresponding MR on cbmroot side is computing/cbmroot!2098, which still need to be rebased and fixed to match the changes done here