runner/kmemleak: library to interact with kmemleak

Adds a simple library for interacting with kmemleak and add
unit testing for the library. There are two modes intended to
integrate with igt_runner:
 - once: collect kmemleaks after all test completed
 - each: collect kmemleaks after eachb test completes

Cc: vitaly.prosyak@amd.com
Cc: christian.koenig@amd.com
Cc: alexander.deucher@amd.com
Cc: jesse.zhang@amd.com
Cc: harry.wentland@amd.com
Cc: zbigniew.kempczynski@intel.com
Cc: kamil.konieczny@linux.intel.com
Cc: ryszard.knop@intel.com
Cc: lucas.demarchi@intel.com
Cc: katarzyna.piecielska@intel.com
Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Signed-off-by: Peter Senna Tschudin <peter.senna@linux.intel.com>
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>