I was not a huge fan of how rlimits were specified using the OCI type as
it just takes in strings for the type which isn't super ergonomic. This
adds a new type for rlimits that we can convert to oci type like we
already do for capabilities.
As a first step to making a pod type, move the nested process
configuration out of LinuxContainer.Configuration.Process and into a
standalone LinuxProcessConfiguration type.
Danny Canter