Add rare tau decay HLT2 lines

The merge request adds several HLT2 lines for rare tau decays.

The following modes are included:

- Tau -> Mu Mu Mu
- Tau -> Mu Mu E (OS+SS)
- Tau -> Mu E E (OS+SS)
- Tau -> E E E
- Tau -> P Mu Mu (OS+SS)
- Tau -> (Phi(1020) -> K K) Mu
- Tau -> Mu Mu Mu Mu Mu
- Tau -> Mu Mu Mu Mu Mu Mu Mu

The following control modes are included:

- Ds -> (Phi -> Mu Mu) Pi
- Ds -> (Phi -> E E) Pi

Rates are measured on testfiledb_key: upgrade_minbias_hlt1_filtered:

Hlt2RD_DsToPhiPi_PhiToEE_LineDecision  	   Incl: 0.0  +/- 0.0  kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_DsToPhiPi_PhiToMuMu_LineDecision	   Incl: 0.0  +/- 0.0  kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauTo5Mu_LineDecision           	   Incl: 0.06 +/- 0.06 kHz, Excl: 0.06 +/- 0.06 kHz
Hlt2RD_TauTo7Mu_LineDecision           	   Incl: 0.0  +/- 0.0  kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToEEE_LineDecision           	   Incl: 0.06 +/- 0.06 kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToMuEE_LineDecision          	   Incl: 0.06 +/- 0.06 kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToMuMuE_LineDecision         	   Incl: 0.06 +/- 0.06 kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToMuMuMu_LineDecision        	   Incl: 0.0  +/- 0.0  kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToPMuMu_LineDecision         	   Incl: 0.0  +/- 0.0  kHz, Excl: 0.0  +/- 0.0  kHz
Hlt2RD_TauToPhiMu_LineDecision         	   Incl: 0.20 +/- 0.11 kHz, Excl: 0.20 +/- 0.11 kHz

Hlt2 Total:                                Rate:	  0 +/- 0.1  kHz

Efficiencies for some modes are measured on simulation and summarized in efficiencies.pdf