dummy: Create a Dummy CNI plugin that creates a virtual interface.

Leverages the Linux dummy interface type to create network interfaces
that permists routing packets through the Linux kernel without
them being transmitted.

This solution allows use of arbitrary non-loopback IP addresses within
the container.

Related to #466

Signed-off-by: Mircea Iordache-Sica <mircea@arista.com>

plugins/main/dummy/README.md

@@ -0,0 +1,39 @@
+---
+title: dummy plugin
+description: "plugins/main/dummy/README.md"
+date: 2022-05-12
+toc: true
+draft: true
+weight: 200
+---
+
+## Overview
+
+dummy is a useful feature for routing packets through the Linux kernel without transmitting.
+
+Like loopback, it is a purely virtual interface that allows packets to be routed to a designated IP address. Unlike loopback, the IP address can be arbitrary and is not restricted to the `127.0.0.0/8` range.
+
+## Example configuration
+
+```json
+{
+	"name": "mynet",
+	"type": "dummy",
+	"ipam": {
+		"type": "host-local",
+		"subnet": "10.1.2.0/24"
+	}
+}
+```
+
+## Network configuration reference
+
+* `name` (string, required): the name of the network.
+* `type` (string, required): "dummy".
+* `ipam` (dictionary, required): IPAM configuration to be used for this network.
+
+## Notes
+
+* `dummy` does not transmit packets.
+Therefore the container will not be able to reach any external network.
+This solution is designed to be used in conjunction with other CNI plugins (e.g., `bridge`) to provide an internal non-loopback address for applications to use.