Implement liveliness support #1874

Job	Run time
Check codebase format with clang-format	9s
Check c99 compilation	13s
Test examples without router	16s
Build raweth transport on ubuntu-latest	21s
Run unit tests on ubuntu-latest	30s
Check compilation with unstable API	15s
Build Zenoh from source	5m 34s
Build and test in single thread on ubuntu-latest	32s
Modular build on ubuntu-latest (1, 1, 1, 1)	37s
Test multicast and unicast fragmentation	49s
Modular build on ubuntu-latest (1, 1, 1, 0)	36s
Test attachments	39s
Test examples memory leak	1m 24s
Modular build on ubuntu-latest (1, 1, 0, 1)	45s
Modular build on ubuntu-latest (1, 1, 0, 0)	42s
Modular build on ubuntu-latest (1, 0, 1, 1)	49s
Modular build on ubuntu-latest (1, 0, 1, 0)	37s
Modular build on ubuntu-latest (1, 0, 0, 1)	36s
Modular build on ubuntu-latest (1, 0, 0, 0)	37s
Modular build on ubuntu-latest (0, 1, 1, 1)	26s
Modular build on ubuntu-latest (0, 1, 1, 0)	22s
Modular build on ubuntu-latest (0, 1, 0, 1)	26s
Modular build on ubuntu-latest (0, 1, 0, 0)	46s
Modular build on ubuntu-latest (0, 0, 1, 1)	27s
Modular build on ubuntu-latest (0, 0, 1, 0)	27s
Modular build on ubuntu-latest (0, 0, 0, 1)	32s
Modular build on ubuntu-latest (0, 0, 0, 0)	23s
	19m 50s

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