ICU-22549 Add DateTimePatternGenerator fuzzer #1244

Job	Run time
clang-valgrind-test	9m 48s
clang-valgrind-intltest (utility)	6m 37s
clang-valgrind-intltest (normalize)	6m 9s
clang-valgrind-intltest (collator)	4m 57s
clang-valgrind-intltest (regex)	5m 0s
clang-valgrind-intltest (format)	16m 24s
clang-valgrind-intltest (translit)	6m 3s
clang-valgrind-intltest (rbbi)	7m 3s
clang-valgrind-intltest (rbnf)	6m 22s
clang-valgrind-intltest (rbnfrt)	6m 15s
clang-valgrind-intltest (icuserv)	5m 24s
clang-valgrind-intltest (idna)	4m 47s
clang-valgrind-intltest (convert)	6m 54s
clang-valgrind-intltest (rbnfp)	5m 18s
clang-valgrind-intltest (csdet)	5m 10s
clang-valgrind-intltest (spoof)	5m 0s
clang-valgrind-intltest (bidi)	5m 23s
	1h 52m 34s

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