examples: freemodbus add tcp support for common master/slave iface

Add TCP port files to provide Modbus TCP interface for communication
Add freemodbus add tcp support for common master/slave iface and tcp example based on socket API
The communication between master and slave checked for each example serial_master, serial_slave (use ModbusPoll TCP)
update tcp example according netif changes, fix ci issues
update TCP slave implementation
update example_test.py to to set IP through stdin
update API documentation
event bit instead of semahore to lock communication resource
update default options and master/slave port files

Closes https://github.com/espressif/esp-idf/issues/858
Closes IDF-452

examples/protocols/modbus/tcp/mb_tcp_slave/main/Kconfig.projbuild

@@ -0,0 +1,18 @@
+menu "Modbus Example Configuration"
+
+    config MB_SLAVE_ADDR
+        int "Modbus slave address"
+        range 1 127
+        default 1
+        help
+            This is the Modbus slave address in the network.
+            The address is used as an index to resolve slave ip address.
+
+    config MB_MDNS_IP_RESOLVER
+        bool "Resolve slave addresses using mDNS service"
+        default y
+        help
+            This option allows to use mDNS service to resolve IP addresses of the Modbus slaves.
+            If the option is disabled the ip addresses of slaves are defined in static table.
+
+endmenu