What is the problem you're trying to solve

We are trying to keep my CNI plugins separate from the ones provided by the CNI project. Some times we also would like to keep CNI conf files in a separate directory.

Describe the solution you'd like

Could Containerd to support the following:

[plugins.'io.containerd.cri.v1.runtime'.cni]
      bin_dir = ['/opt/cni/bin', '/opt/local/cni/bin']
      cggonf_dir = ['/etc/cni/net.d', '/usr/local/etc/cnit/net.d']
      max_conf_num = 1
      setup_serially = false
      conf_template = ''
      ip_pref = ''
      use_internal_loopback = false

Additional context

No response