WIP: Add libcoap CoapUdpIpChannel

[LasseRosenow]

This adds a libcoap based CoapUdpIpChannel for federated communication on the POSIX target.

This is still rough and needs more testing.

For now the super basic unit tests proves that communication between the client and the server through the NetworkChannel API works.

TODO:

• Implement the fully integrated runtime integration test
• Make all tests pass
• Fix bugs
• Cleanup Code
• Fix HORRIBLE CMAKE HACKS 😭😭😭😭😭😭

[github-actions]

Benchmark results after merging this PR:

Benchmark results

Performance:

PingPongUc:
Best Time: 243.586 msec
Worst Time: 245.770 msec
Median Time: 243.778 msec

PingPongC:
Best Time: 171.903 msec
Worst Time: 179.366 msec
Median Time: 172.486 msec

ReactionLatencyUc:
Best latency: 40105 nsec
Median latency: 61222 nsec
Worst latency: 270909 nsec

ReactionLatencyC:
Best latency: 23110 nsec
Median latency: 61001 nsec
Worst latency: 100367 nsec

Memory usage:

PingPongUc:
text data bss dec hex filename
37298 760 8472 46530 b5c2 bin/PingPongUc

PingPongC:
text data bss dec hex filename
45826 880 360 47066 b7da bin/PingPongC

ReactionLatencyUc:
text data bss dec hex filename
23539 736 2520 26795 68ab bin/ReactionLatencyUc

ReactionLatencyC:
text data bss dec hex filename
41536 848 360 42744 a6f8 bin/ReactionLatencyC