ICU-22843 UnicodeString <-> std::u16string_view / wstring_view #2476

Job	Run time
clang-valgrind-test	10m 14s
clang-valgrind-intltest (utility)	7m 20s
clang-valgrind-intltest (normalize)	6m 11s
clang-valgrind-intltest (collator)	5m 7s
clang-valgrind-intltest (regex)	5m 52s
clang-valgrind-intltest (format)	16m 53s
clang-valgrind-intltest (translit)	5m 46s
clang-valgrind-intltest (rbbi)	7m 48s
clang-valgrind-intltest (rbnf)	6m 1s
clang-valgrind-intltest (rbnfrt)	6m 14s
clang-valgrind-intltest (icuserv)	5m 33s
clang-valgrind-intltest (idna)	5m 11s
clang-valgrind-intltest (convert)	6m 44s
clang-valgrind-intltest (rbnfp)	5m 36s
clang-valgrind-intltest (csdet)	5m 17s
clang-valgrind-intltest (spoof)	5m 29s
clang-valgrind-intltest (bidi)	5m 30s
	1h 56m 46s

Provide feedback