app/test-sad: add test application for IPsec SAD

app/test-sad: add test application for IPsec SAD

Introduce new application to provide user to evaluate and perform
custom functional and performance tests for IPsec SAD implementation.

According to our measurements on SKX for 1M entries average lookup
cost is ~80 cycles, average add cost ~500 cycles.

Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Tested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>