Add the property backend and a setprop builtin so that setting a
property can feed action triggers. property_simple.c provides a minimal
init_property_*() implementation whose init_property_set() forwards the
key/value pair to init_action_trigger_event(), and init.c wires the
property poller into the init poll loop.
Signed-off-by: fangpeina <fangpeina@xiaomi.com>
Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>