HVMux compatibiity for end-cap R4 and R5

The end-cap R4 and R5 powerboards have two HVMuxes. These are connected to HVMux-0 and HVMux-2 on the AMAC. This MR does the following:

• add the option to select the HVMux to run on in the testHvEnable and measureHvSense
• change the QC flow such that both HVMuxes are tested if the PB type is R4 or R5
• merge the test results of the two HVMuxes. The results of the second HVMux are thereby indicated by the string HV2 in the result

Depends on !157 (merged) and !158 (merged)

Tagging @kkrizka