Replace all manually handled mounts with containerd's mount helper

[cmainas]

Containerd provides the https://pkg.go.dev/github.com/containerd/containerd/mount package with helper functions for mounting files and directories. Therefore with the work from #824 we can replace the logic we have with the manual mounting of files and directories with the contianerd's package, which can be trusted more than our code.

[shivansh-source]

@cmainas can i work on this