Add cycle-clean option in AppLaunch

If cycle-clean is enabled then all the apps will be
killed at the end of the cycle and cache will dropped.

Cycle time is also enabled to measure the sum of launch times
during each cycle.

Above two options will enable use to measure app launch time under
memeory pressue by not killing the app between the launches and
by killing all the apps and dropping the cache before each cycle
and measuring the cycle time.

Bug: b/73091210

Tested : Tested with nodropcache, no force stop between launches
and cycle clean option and the cycle time avg,min and max
is printed as expected.

Change-Id: I8fb22439a9fe191104ce024c8a85a2688068cd60