ICU-22979 Support inverse rule for [] span in RBNF #3320

Job	Run time
clang-valgrind-intltest (utility)	6m 58s
clang-valgrind-test	10m 13s
clang-valgrind-intltest (normalize)	6m 58s
clang-valgrind-intltest (collator)	5m 34s
clang-valgrind-intltest (regex)	5m 23s
clang-valgrind-intltest (format)	16m 25s
clang-valgrind-intltest (translit)	6m 33s
clang-valgrind-intltest (rbbi)	8m 32s
clang-valgrind-intltest (rbnf)	6m 27s
clang-valgrind-intltest (rbnfrt)	6m 11s
clang-valgrind-intltest (icuserv)	5m 32s
clang-valgrind-intltest (idna)	5m 39s
clang-valgrind-intltest (convert)	6m 58s
clang-valgrind-intltest (rbnfp)	5m 24s
clang-valgrind-intltest (csdet)	5m 22s
clang-valgrind-intltest (spoof)	5m 16s
clang-valgrind-intltest (bidi)	5m 35s
	1h 59m 0s

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