merge-ktd-beta from branch/tag: ktd-beta into branch: lakitu-4.19

Changelog:
-------------------------------------------------------------

Richard Guy Briggs (1):
      audit: add container id

Thomas Garnier (5):
      security: Add task_exit LSM hook
      security: add LSM task_post_alloc hook to copy_process
      security: add LSM file pre-free hook to be compatible with 4.19
      security: track kubectl/docker exec session using pid_namespace field
      security: Container Monitoring LSM

BUG=b:148390640
TEST=tryjob, validation and K8s e2e
SOURCE=KTD

Signed-off-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Change-Id: Ied2db48690d40083366a7b91fd35654c220a135d