icu: bump to 78.1

icu: bump to 78.1

Update to 78.1

ICU 78 updates to Unicode 17 (blog), including new characters and scripts, emoji, collation & IDNA changes, and corresponding APIs and implementations.

It also updates to CLDR 48 (blog) locale data with new locales, and various additions and corrections.

In C++, there is a new set of APIs for Unicode string (UTF-8/16/32) code point iteration that works seamlessly with modern C++ iterators and ranges.

The C++ implementation of MessageFormat 2.0 is at CLDR 47 level and remains in technology preview.

ICU 78 and CLDR 48 are major releases, including a new version of Unicode and major locale data improvements.

Signed-off-by: Hirokazu MORIKAWA <[email protected]>