Optionally collect metrics from rpc requests and responses (#982) #297

Job	Run time
jammy/g++/c++17/asan=off/ubsan=off	9m 24s
focal/clang++/c++17/asan=off/ubsan=on	8m 32s
focal/g++-10/c++20/asan=on/ubsan=off	10m 4s
	28m 0s

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