This PR is for fixing error found in integration testing for Bootstrap and Connector functionality.
The corresponding fixes done here
6925e89487fbfb300d62
Replacing with source code replicated from respective repositories including
mbed-client - TAG mbed-os-5.0-rc1
mbed-client-c - TAG mbed-os-5.0-rc1
mbed-client-classic - TAG mbed-os-5.0-rc2
mbed-client-mbed-tls - TAG mbed-os-5.0-rc1
mbed-client-randlib - TAG mbed-os-5.0-rc1
coap-service - TAG mbed-os-5.0-rc1
Adding CONTRIBUTING.md file explaining how to submit patches for any of the components belonging to FEATURE_CLIENT