battery.c now uses the zmk,battery chosen node to select a battery
sensor. Using the node labeled "BATTERY" is maintained for backwards
compatibility but is now deprecated. Custom boards should switch to
using the chosen node.
# Conflicts:
# app/boards/arm/bluemicro840/bluemicro840_v1.dts
# app/boards/arm/nice60/nice60.dts
# app/boards/arm/nrfmicro/nrfmicro_13.dts
# Conflicts:
# app/boards/arm/bluemicro840/bluemicro840_v1.dts
