Add EXEC command to run commands inside containers

Add EXEC command to run commands inside containers: a task in LegoFlow-SWE (Harbor dataset). Pumba currently supports STOP and KILL commands for Docker containers. These commands prevent Docker’s restart policy from taking effect — containers killed or stopped by Pumba are not automatically…

The task

Pumba currently supports `STOP` and `KILL` commands for Docker containers. These commands prevent Docker’s restart policy from taking effect — containers killed or stopped by Pumba are **not** automatically restarted, even when a restart policy is configured. This makes it impossible to simulate process crashes…

Part of Lego-X/LegoFlow-SWE.