Current lwip implementation does not support deleting a task which is
actively waiting on `select()` or `poll()` API.
Therefore we have to make sure that `select()` exits to deallocate its internal
callback before deleting the task. This is achieved by a shutdown
semaphore which informs the client once the `select()` exitted.
fix slave
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
