OPENTHREAD_CONFIG_DEVICE_POWER_SUPPLY macro

@def OPENTHREAD_CONFIG_DEVICE_POWER_SUPPLY Specifies the default device power supply config. This config MUST use values from `otPowerSupply` enumeration. Device manufacturer can use this config to set the power supply config used by the device. This is then used as part of default `otDeviceProperties` to determine the Leader Weight used by the device.