## What changed
Add `third_party/v8/icu.BUILD.bazel` and wire V8's ICU repository to use it instead of patching upstream `bazel/BUILD.icu`.
Select ICU's custom libc++ flags and runtime dependencies through `//third_party/v8:use_rusty_v8_custom_libcxx`, keeping ICU aligned with V8 and its host generators.
GitOrigin-RevId: 92a1b883f5d42d9a3a464002e922295ab166f2bd