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
add support of modbus master ascii
rename base dir name of master and slave example to be mb_slave, mb_master to avoid conflict with sdio/slave example test
add Kconfig option to enable ASCII and RTU mode separately
update ASCII options + remove cast for errors
added baudrate for examples into Kconfig
updated magic numbers for timer timeout
put ascii private definitions into one file
