Support CNI bridge plugin
If the CNI_BRIDGE environment variable is set (whatever value), kindnet will use the CNI bridge plugin.
If not set, it defaults to the CNI ptp plugin.
A new manifest to install kindnet using the CNI bridge is provided
https://github.com/aojea/kindnet/blob/master/install-kindnet-bridge.yaml
Full Changelog: v0.8.0...v0.8.1