Use client earlyCapabilities to determine channel join count #1153

Job	Run time
code formatting check	17s
cppcheck	4m 8s
min features with gcc	2m 58s
min features with g++	2m 33s
min features with clang	2m 44s
max features with gcc	3m 6s
max features with g++	1m 49s
max features with clang	3m 21s
max features with gcc and DEBUG	2m 8s
max features with gcc for 32-bit arch (legacy OS)	2m 9s
max features with g++ for 32-bit arch (legacy OS)	1m 47s
max features with clang for 32-bit arch (legacy OS)	1m 56s
	28m 56s

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