Rpc client u subscription #87

Job	Run time
Build up-cpp and dependencies	1m 36s
Run up-cpp tests	14s
Run Valgrind Memcheck	3m 24s
Lint C++ sources	2m 59s
Run Valgrind Helgrind	2m 41s
Run Valgrind DHAT	1m 52s
Run Valgrind ThreadCheck	2m 29s
CI status checks	2s
	15m 17s

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