By removing the definition of the NetworkContext struct in the header file, we allow the application to define it. This allows an application writer to use multiple transports in the same compilation unit. That way, multiple .c files do not have to be created for each transport.
A new repository, FreeRTOS/backoffAlgorithm, has been created for hosting the library for backoff calculation. This repo replaces the FreeRTOS-Plus/Source/Utilities/exponential_backoff with the submodule to the new repository, and updates all the demos that use retry logic to use the backoffAlgorithm API
