Add y-cable driver for simulated mux

setup.py

@@ -26,6 +26,7 @@
         'sonic_y_cable',
         'sonic_y_cable.credo',
         'sonic_y_cable.broadcom',
+        'sonic_y_cable.microsoft'
     ],
     # NOTE: Install also depends on sonic-config-engine for portconfig.py
     # This dependency should be eliminated by moving portconfig.py

sonic_y_cable/microsoft/README

@@ -0,0 +1,18 @@
+# Design of y-cable driver implemented multiple vendor API for mux simulator
+
+The mux simulator exposes a set of APIs for the client. To access the APIs, the client needs to know some key information:
+1. The mux simulator server IP and port
+2. The vm_set information
+3. The port index
+
+Port index is know to the y-cable driver. So, we need to pass items #1-#3 to the y-cable driver. We can update the existing [test_inject_y_cable_simulator_client](https://github.com/Azure/sonic-mgmt/blob/master/tests/test_pretest.py#L182) test case to pass server IP/port and vm_set information to the DUT during pretest.
+
+Simply create a json file to `/etc/sonic/mux_simulator.json` with content like
+```
+{
+    "server_ip": "192.168.0.10",
+    "server_port": "8000",
+    "vm_set": "vms17-7",
+    "side": "upper_tor"
+}
+```