feat(ext power): Support multiple ext_power GPIOS #1527

Job	Run time
get-changed-files	4s
get-grouped-hardware	9s
core-coverage	8s
nightly	0s
board-changes	0s
compile-matrix	1s
build (nice_nano_v2, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shiel...	6m 47s
build (nrfmicro_13, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield...	3m 0s
build (proton_c, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield":"...	2m 49s
build (bdn9_rev2, [{},{"cmake-args":"-DCONFIG_ZMK_STUDIO=y","snippet":"studio-rpc-usb-uart","nick...	1m 48s
build (nice60, [{}])	1m 48s
build (seeeduino_xiao_ble, [{"shield":"hummingbird"}])	1m 36s
build (nrf52840_m2, [{"shield":"m60"}])	1m 34s
build (planck_rev6, [{}])	1m 54s
build (sparkfun_pro_micro_rp2040, [{"shield":"reviung41","cmake-args":"-DSNIPPET='zmk-usb-logging...	1m 39s
build (nice_nano, [{"shield":"romac_plus","cmake-args":"-DCONFIG_ZMK_RGB_UNDERGLOW=y -DCONFIG_WS2...	1m 46s
build (seeeduino_xiao, [{"shield":"hummingbird","cmake-args":"-DCONFIG_ZMK_STUDIO=y","snippet":"s...	1m 24s
	26m 27s

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