ICU-22979 Support inverse rule for [] span in RBNF #3338

Job	Run time
clang-valgrind-test	10m 24s
clang-valgrind-intltest (utility)	7m 8s
clang-valgrind-intltest (normalize)	6m 23s
clang-valgrind-intltest (collator)	5m 58s
clang-valgrind-intltest (regex)	5m 48s
clang-valgrind-intltest (format)	16m 28s
clang-valgrind-intltest (translit)	6m 10s
clang-valgrind-intltest (rbbi)	7m 58s
clang-valgrind-intltest (rbnf)	6m 33s
clang-valgrind-intltest (rbnfrt)	6m 16s
clang-valgrind-intltest (icuserv)	5m 25s
clang-valgrind-intltest (idna)	5m 36s
clang-valgrind-intltest (convert)	7m 9s
clang-valgrind-intltest (rbnfp)	5m 40s
clang-valgrind-intltest (csdet)	5m 14s
clang-valgrind-intltest (spoof)	5m 33s
clang-valgrind-intltest (bidi)	5m 31s
	1h 59m 14s

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