What is the problem you're trying to solve
Containers run that rely on containerd and containerd's packages may be running a platform different than the host. For example, linux containers on windows, which run using a lightweight linux virtual machine. When sending signals to a container, we should use signals for the container's platform, not the host's.

Describe the solution you'd like
We parse signals based on the container's platform.

Additional context
I previously made a PR to accomplish this here, but it fell off and eventually was closed. Recently, this PR was made to remove signal parsing in containerd in favor of using moby/sys platform parsing in here.