libicu v78 formatting changes

[ShortDevelopment]

The following Intl test started failing in MacOS ci likely to the new libicu v78.1 (see https://github.com/chakra-core/ChakraCore/pull/7038#issuecomment-3591893684)

https://github.com/chakra-core/ChakraCore/blob/2dba810c925eb366e44a1f7d7a5b2e289e2f8510/test/Intl/DateTimeFormat.js#L207-L208

ci-linux.txt ci-macos.txt

ChakraCore

CC generates a skeleton in javascript

https://github.com/chakra-core/ChakraCore/blob/2dba810c925eb366e44a1f7d7a5b2e289e2f8510/lib/Runtime/Library/InJavascript/Intl.js#L1746-L1746 https://github.com/chakra-core/ChakraCore/blob/2dba810c925eb366e44a1f7d7a5b2e289e2f8510/lib/Runtime/Library/InJavascript/Intl.js#L1295-L1459

and uses udatpg_getBestPattern to let libicu generate an appropriate pattern.

https://github.com/chakra-core/ChakraCore/blob/2dba810c925eb366e44a1f7d7a5b2e289e2f8510/lib/Runtime/Library/IntlEngineInterfaceExtensionObject.cpp#L2800 https://github.com/chakra-core/ChakraCore/blob/2dba810c925eb366e44a1f7d7a5b2e289e2f8510/lib/Runtime/Library/IntlEngineInterfaceExtensionObject.cpp#L2843-L2851

libicu

The table below shows the behavior changes of udatpg_getBestPattern (de-DE is just for additional context) Notice the missing , in en-US v78.1.

version	locale	skeleton	pattern
v77.1	en-US	EEEEh	cccc, h/a
		cccch	cccc, h/a
	de-DE	EEEEh	cccc, h 'Uhr' a
		cccch	cccc, h 'Uhr' a
v78.1	en-US	EEEEh	EEEE h/a
		cccch	EEEE h/a
	de-DE	EEEEh	EEEE, h/a
		cccch	EEEE, h/a

[ShortDevelopment]

https://unicode-org.atlassian.net/browse/CLDR-19139