feat(behaviors): Add a send string behavior #5469

Job	Run time
get-changed-files	2s
get-grouped-hardware	7s
core-coverage	7s
board-changes	0s
nightly	0s
compile-matrix	2s
build (nice_nano_v2, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shiel...	6m 38s
build (nrfmicro_13, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield...	4m 10s
build (proton_c, [{"shield":"corne_left"},{"shield":"corne_right"},{"shield":"romac"},{"shield":"...	2m 47s
build (bdn9_rev2, [{}])	1m 58s
build (nice60, [{}])	2m 0s
build (seeeduino_xiao_ble, [{"shield":"hummingbird"}])	2m 38s
build (nrf52840_m2, [{"shield":"m60"}])	2m 20s
build (planck_rev6, [{}])	1m 36s
build (nice_nano, [{"shield":"romac_plus","cmake-args":"-DCONFIG_ZMK_RGB_UNDERGLOW=y -DCONFIG_WS2...	2m 0s
	26m 25s

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