Add support for COUNT and fix a bug in the GROUP BY HashMap optimization #3672

Job	Run time
build (gcc, 11, -Wall -Wextra -Werror , Release, true)	30m 2s
build (gcc, 12, -Wall -Wextra -Werror , Release, true)	31m 52s
build (gcc, 13, -Wall -Wextra -Werror , Release, true)	28m 47s
build (clang, 16, -Wall -Wextra -Werror , Release, true)	33m 34s
build (clang, 17, -Wall -Wextra -Werror , Release, true)	32m 29s
build (clang, 16, Release, false, -fsanitize=address -fno-omit-frame-pointer)	41m 11s
build (clang, 16, Release, false, -fsanitize=undefined)	40m 4s
build (clang, 17, Debug, false, -fsanitize=thread -O1 -g)	43m 41s
	4h 41m 40s

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