build: add libicui18n library for clang
build: add libicui18n library for clang

The build with clang fails with

  ld.lld: error: undefined symbol: icu_65::Collator::createInstance(icu_65::Locale const&, UErrorCode&)
  >>> referenced by like_matcher.cc
  >>>               build/dev/utils/like_matcher.o:(boost::re_detail_106900::icu_regex_traits_implementation::icu_regex_traits_implementation(icu_65::Locale const&))
  >>> referenced by like_matcher.cc
  >>>               build/dev/utils/like_matcher.o:(boost::re_detail_106900::icu_regex_traits_implementation::icu_regex_traits_implementation(icu_65::Locale const&))

That symbol lives in libicui18n. It's not clear why clang fails to resolve it and gcc succeeds (after all,
both use lld as the linker) but it is easier to add the library than to attempt to figure out the
discrepancy.

Closes #7391

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla