samples/damon/wsse: start and stop DAMON as the user requests

Start running DAMON to monitor accesses of a process that the user
specified via 'target_pid' parameter, when 'y' is passed to 'enable'
parameter.  Stop running DAMON when 'n' is passed to 'enable' parameter. 
Estimating the working set size from DAMON's monitoring results and
reporting it to the user will be implemented by the following commit.

Link: https://lkml.kernel.org/r/20241210215030.85675-3-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>