Add lampTest class for LED

- Add the framework of the lamp test class.

- For the lamp test path in led group, Initiate lamp test when the
  Asserted property is true, Stop the lamp test when the Asserted
  property is false or the timer expires.

Tested:
- stat lamp test:
  busctl set-property xyz.openbmc_project.LED.GroupManager
  /xyz/openbmc_project/led/groups/lamp_test
  xyz.openbmc_project.Led.Group  Asserted b true

- stop lamp test:
  busctl set-property xyz.openbmc_project.LED.GroupManager
  /xyz/openbmc_project/led/groups/lamp_test
  xyz.openbmc_project.Led.Group  Asserted b false

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I7e6fe0ffc4679288ab90050742d2680051e61905
7 files changed