ztest: Add config to shuffle test order

Enable ZTEST_DO_THE_SHUFFLE to shuffle the order tests are ran.
Additional configs ZTEST_DO_THE_SHUFFLE_SUITE_REPEAT_COUNT
ZTEST_DO_THE_SHUFFLE_TEST_REPEAT_COUNT specify the number of times
the test or suite is executed.

Signed-off-by: Al Semjonovs <asemjonovs@google.com>