ICU-22493 Implement First Day Override in Calendar #1227

Job	Run time
clang-valgrind-test	10m 0s
clang-valgrind-intltest (utility)	6m 45s
clang-valgrind-intltest (normalize)	6m 20s
clang-valgrind-intltest (collator)	5m 3s
clang-valgrind-intltest (regex)	5m 14s
clang-valgrind-intltest (format)	16m 29s
clang-valgrind-intltest (translit)	6m 4s
clang-valgrind-intltest (rbbi)	6m 58s
clang-valgrind-intltest (rbnf)	6m 22s
clang-valgrind-intltest (rbnfrt)	6m 17s
clang-valgrind-intltest (icuserv)	5m 19s
clang-valgrind-intltest (idna)	5m 13s
clang-valgrind-intltest (convert)	6m 52s
clang-valgrind-intltest (rbnfp)	5m 38s
clang-valgrind-intltest (csdet)	5m 30s
clang-valgrind-intltest (spoof)	5m 41s
clang-valgrind-intltest (bidi)	5m 17s
	1h 55m 2s

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