ICU-22549 Add fuzzer for NumberFormatter #1260

Job	Run time
clang-valgrind-intltest (utility)	6m 28s
clang-valgrind-test	9m 53s
clang-valgrind-intltest (normalize)	6m 5s
clang-valgrind-intltest (collator)	5m 10s
clang-valgrind-intltest (regex)	5m 15s
clang-valgrind-intltest (format)	16m 13s
clang-valgrind-intltest (translit)	5m 59s
clang-valgrind-intltest (rbbi)	8m 14s
clang-valgrind-intltest (rbnf)	6m 17s
clang-valgrind-intltest (rbnfrt)	6m 0s
clang-valgrind-intltest (icuserv)	5m 7s
clang-valgrind-intltest (idna)	5m 9s
clang-valgrind-intltest (convert)	6m 20s
clang-valgrind-intltest (rbnfp)	5m 18s
clang-valgrind-intltest (csdet)	5m 18s
clang-valgrind-intltest (spoof)	5m 7s
clang-valgrind-intltest (bidi)	5m 26s
	1h 53m 19s

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