release-45-beta4

CLDR-17541 Update README status/data & spec date, update CLDR poms for final (#3635)
CLDR-16938 Restore _header.txt file (#3636)
CLDR-17504 fix recursive update in XPathParts (#3631)
CLDR-16938 fix test file headers (#3630)
CLDR-17490 generate validity for units 2 (#3628)
CLDR-17424 MFv2 spec: link fix, style improvement (#3629)
CLDR-17424 v45: mfwg2 spec pour (#3626)
CLDR-17202 kbd: add a Hiragana Flick keyboard (#3574)
CLDR-17416 v45 docs: fix ToCs (#3620)
CLDR-17367 v45 JSON: improve localeRules processing (#3611)
CLDR-17341 v45: kbd spec: editorial improvements (#3618)
CLDR-17512 Update ICU4J version to 75.1-SNAPSHOT (#3613)
CLDR-17482 Fix million compact number issue in Italian (#3612)
CLDR-17500 Update README date & status, fix spec date (#3610)