net: shell: Add support for 'net tcp recv' command
net: shell: Add support for 'net tcp recv' command

Add command to register a receive callback to the net_context used for
the TCP connection that is opened with 'net tcp connect'. The receive
callback will simply print the number of bytes received and inform if
the connection is closed. This makes it possible to test both the tx
and rx paths with the net shell.

Signed-off-by: Tobias Svehagen <d3302b125bdd383498bbe4afb41749ba75a64b52@gmail.com>

finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr