This commit includes:
* Add support for sending response to duplicate messages
* Add randomness for retransmission time
* Fix usage sn coap blockwise max time data stored
* CoAP parser option handler does not seem to handle "Option Length" completely according to spec
* Handle '0' value if duplication buffer size is set through the sn_coap_protocol_set_duplicate_buffer_size()
This commit includes
- Removing CoAP sources from mbed-client-c to its own repository.
- mbed-client-c is moved outside of mbed-os source tree because it is used by mbed-client, so
it will be part of mbed-client offering.
- CoAP sources are used by coap-service which is a part of nanostack deliveries hence coap now existing
as independent module under mbed-coap.
- Commit handles the interdepdency of coap-service with mbed-client-c because of coap sources, coap-service
header files are now fixed to point to right header directory.
Antti Yli-Tokola
Yogesh Pande