ICU-22979 Support inverse rule for [] span in RBNF #3309

Job	Run time
clang-valgrind-test	10m 27s
clang-valgrind-intltest (utility)	6m 50s
clang-valgrind-intltest (normalize)	6m 27s
clang-valgrind-intltest (collator)	6m 3s
clang-valgrind-intltest (regex)	5m 48s
clang-valgrind-intltest (format)	16m 20s
clang-valgrind-intltest (translit)	6m 3s
clang-valgrind-intltest (rbbi)	8m 29s
clang-valgrind-intltest (rbnf)	6m 21s
clang-valgrind-intltest (rbnfrt)	6m 18s
clang-valgrind-intltest (icuserv)	5m 34s
clang-valgrind-intltest (idna)	5m 51s
clang-valgrind-intltest (convert)	7m 8s
clang-valgrind-intltest (rbnfp)	5m 24s
clang-valgrind-intltest (csdet)	5m 16s
clang-valgrind-intltest (spoof)	5m 33s
clang-valgrind-intltest (bidi)	5m 54s
	1h 59m 46s

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