Support multi power buttons with multi behaviors

For supporting more-than-one power buttons behaviors,
add new matches and instances by following json config.

This change is for multiple slots integrated on one chassis,
and each slot has button to control power status.

For example:
/xyz/openbmc_project/Chassis/Buttons/Power01 for button on slot1
/xyz/openbmc_project/Chassis/Buttons/Power02 for button on slot2

Moreover, support multi-level power control by json config,
chassis now can do action by corresponding pressing duration.

Tested:
Press buttons and check corresponding behaviors.

Change-Id: I7789f0367d5e846dd9e68f966ba0755fc916217a
Signed-off-by: Rush Chen <rush.chen.wiwynn@gmail.com>
diff --git a/inc/host_then_chassis_poweroff.hpp b/inc/host_then_chassis_poweroff.hpp
index 96d7aee..cf29a4a 100644
--- a/inc/host_then_chassis_poweroff.hpp
+++ b/inc/host_then_chassis_poweroff.hpp
@@ -61,7 +61,7 @@
      * @brief Returns the name that matches the value in
      *        meson_options.txt.
      */
-    static constexpr std::string_view getName()
+    static constexpr std::string getName()
     {
         return "host_then_chassis_poweroff";
     }