Multipacket

[GwendalRaoul]

Brief description

Implement collection of generic message.

• Gateway is able to group received message
• Gateway can receive multiple requests at the same time

For now groups are defined in the code directly for testing purpose. Dynamic config will be added in one of the next steps.

This change required the PR: https://github.com/wirepas/backend-apis/pull/124

Remaining items

• [ ] .Add grouping configuration (from API and config file)

• [ ] Save group config in case of restart

• [ ] Define the final topics for collection message

• [ ] Fix synchro in packet queue to avoid group of messages exceeding the max number of element

• [ ] Try to determine the final size of a packet group without serializing the message to avoid too much computing (with some margin)