selftests/damon: implement a program for even-numbered memory regions access

selftests/damon: implement a program for even-numbered memory regions access

To test schemes_tried_regions feature, we need to have a program having
specific number of regions that having different access pattern.  Existing
artificial access pattern generator, 'access_memory', cannot be used for
the purpose, since it accesses only one region at a given time.  Extending
it could be an option, but since the purpose and the implementation are
pretty simple, implementing another one from the scratch is better.

Implement such another artificial memory access program that allocates
user-defined number/size regions and accesses even-numbered regions.

Link: https://lkml.kernel.org/r/20240625180538.73134-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>