Update ICU to ICU 70-1 with tests

Size Impact:
Android   +143K
Cast      -143K
ChromeOS  -154.7K
Common    -159K
flutter   -123.1K
iOS       -157.6K
Diary https://docs.google.com/document/d/1NqMw7DAVFCZRx67auC7sgOvrikHvCYuaB87JUf21yG8

Bug: 1260116
Change-Id: I90102bf8c5a9d54a59658b2d2f7fb25b405917ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/3268349
Reviewed-by: Jungshik Shin <jshin@chromium.org>
diff --git a/source/common/brkiter.cpp b/source/common/brkiter.cpp
index b9b6ca6..8b228ac 100644
--- a/source/common/brkiter.cpp
+++ b/source/common/brkiter.cpp
@@ -234,7 +234,7 @@
 public:
     virtual ~ICUBreakIteratorFactory();
 protected:
-    virtual UObject* handleCreate(const Locale& loc, int32_t kind, const ICUService* /*service*/, UErrorCode& status) const {
+    virtual UObject* handleCreate(const Locale& loc, int32_t kind, const ICUService* /*service*/, UErrorCode& status) const override {
         return BreakIterator::makeInstance(loc, kind, status);
     }
 };
@@ -254,11 +254,11 @@
 
     virtual ~ICUBreakIteratorService();
 
-    virtual UObject* cloneInstance(UObject* instance) const {
+    virtual UObject* cloneInstance(UObject* instance) const override {
         return ((BreakIterator*)instance)->clone();
     }
 
-    virtual UObject* handleDefault(const ICUServiceKey& key, UnicodeString* /*actualID*/, UErrorCode& status) const {
+    virtual UObject* handleDefault(const ICUServiceKey& key, UnicodeString* /*actualID*/, UErrorCode& status) const override {
         LocaleKey& lkey = (LocaleKey&)key;
         int32_t kind = lkey.kind();
         Locale loc;
@@ -266,7 +266,7 @@
         return BreakIterator::makeInstance(loc, kind, status);
     }
 
-    virtual UBool isDefault() const {
+    virtual UBool isDefault() const override {
         return countFactories() == 1;
     }
 };