Add support for COUNT and fix a bug in the GROUP BY HashMap optimization #3652

Job	Run time
build (gcc, 11, -Wall -Wextra -Werror , Release, true)	29m 53s
build (gcc, 12, -Wall -Wextra -Werror , Release, true)	32m 42s
build (gcc, 13, -Wall -Wextra -Werror , Release, true)	29m 29s
build (clang, 16, -Wall -Wextra -Werror , Release, true)	33m 3s
build (clang, 17, -Wall -Wextra -Werror , Release, true)	32m 56s
build (clang, 16, Release, false, -fsanitize=address -fno-omit-frame-pointer)	40m 10s
build (clang, 16, Release, false, -fsanitize=undefined)	40m 15s
build (clang, 17, Debug, false, -fsanitize=thread -O1 -g)	42m 47s
	4h 41m 15s

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