Implement GRC::GetAvgNetworkWeight #2050

Job	Run time
ARM [GOAL install] [buster]	2m 42s
Lint	47s
Win32	3m 12s
macOS 12 native [GOAL install] [GUI] [no depends]	7m 4s
Win64	4m 46s
i386 Linux [GOAL install] [focal]	2m 25s
x86_64 Linux [GOAL install] [GUI] [focal] [no depends]	16m 5s
x86_64 Linux [GOAL install] [GUI] [bionic] [no depends]	15m 16s
x86_64 Linux [ASan] [LSan] [UBSan] [integer] [jammy] [no depends]	5m 26s
macOS 10.14 [GOAL deploy] [GUI] [no tests] [noble]	3m 29s
arm64 macOS 10.14 [GOAL deploy] [GUI] [no tests] [noble]	3m 13s
	1h 4m 25s

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