Split into multiple modules to prevent security scanner false positives

[danwinship]

Because all of containernetworking/cni is currently a single go module, a CVE in any dependency (or any part of cni itself) causes fire drills in all packages that use any part of containernetworking/cni. In particular, packages that only import pkg/types (pkg/utils, pkg/ns, etc) get tagged for CVEs that only affect pkg/invoke.

Reorganizing the code and splitting into multiple golang modules will help security scanners avoid these false positives.