plugin-api: resourced: Add is_cpu_contention_alleviated

plugin-api: resourced: Add is_cpu_contention_alleviated

Add is_cpu_contention_alleviated function to check whether
cpu contention is alleviated or not.

Prototype of new function is like below:
  - bool syscommon_plugin_resourced_is_cpu_contention_alleviated(
               guint timer_id, guint latest_timer_id);
    * After a stall event is monitored, a timer with some interval set.
      If no more stall events between setting timer and timeout,
      timer_id is equal to latest_timer_id.

Change-Id: I0136f445827ae49d002fd8dcb0919cef0ada40b9
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>