Use EquipConf for PS definitions

Switch to using the new PowerSupplyChannel and EquipConf classes for customizable power supply configuration inside powertools.

This has the following impact:

• The power supply definitions are stores inside config directory. The user should copy and edit them manually.
• The PBv3TB class has a constructor that takes an EquipConf instance as an argument and retrieves and connects the necessary power supplies from there. There is also a constructor where the power supply pointers can be passed directly, in case one does not want to use EquipConf.
• For EquipConf usage with a testbench, LV power supply channel is called "Vin".
• For EquipConf usage with a testbench, HV power supply is called "HVin".
• The definition file, config/equip_testbench.json, is provided for Powerboard testing with Agilent + Keithley.
• The definition file, config/equip_calib.json, is provided for calibrating the mass tester variable load.
• All tools that require power supply communication take -e/--equip option for specifying the equipment definition file.
• All tests in PBv3TestTools now take IPowerSupply pointers.

Some other changes that were made here:

• The PBv3TB now has a m_hv power supply corresponding to the high voltage PS
• Add more information to pbv3_active_calibrate
• The pbv3_tune program no longer manages power supplies. This makes it a useful tools for situations other than running basic tests (ie: module operations).
• Clean-up of pbv3_active_debug.