feat: Add a way to jump to bootloader on startup #1000

Job	Run time
get-changed-files	7s
get-grouped-hardware	10s
core-coverage	6s
nightly	0s
board-changes	0s
compile-matrix	8s
build (nice_nano_v2, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shiel...	7m 49s
build (nrfmicro_13, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield...	5m 29s
build (proton_c, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield":"...	3m 37s
build (bdn9_rev2, [{}])	1m 37s
build (nice60, [{}])	3m 13s
build (seeeduino_xiao_ble, [{"shield":"hummingbird"}])	2m 30s
build (nrf52840_m2, [{"shield":"m60"}])	2m 46s
build (planck_rev6, [{}])	1m 42s
build (nice_nano, [{"shield":"romac_plus","cmake-args":"-DCONFIG_ZMK_RGB_UNDERGLOW=y -DCONFIG_WS2...	2m 32s
	31m 46s

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