Implement CNI v1.1 for the host-local plugin

[antoninbas]

This is a similar issue as #1013 (which is for the bridge plugin).

In particular, implementing GC may be useful in case of a leaked IPAM reservation. This seems very much in line with the specification for GC:

The GC verb allows runtimes to specify the set of known-good attachments, allowing plugins to clean up stale and leaked resources such as IPAM reservations.

CNI plugins that invoke host-local directly for IPAM would be able to rely on this for their own GC implementation.