Ntuplizer and analysis code for the Tau→3mu search at Run 3

Setting the environment

cmsrel CMSSW_13_0_13 (or CMSSW_12_4_11_patch3 for 2022 preEE data)
cd CMSSW_13_0_13/src
cmsenv
git clone https://github.com/Ma128-bit/Tau3muRun3 .
scram b -j20