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/ubidi.cpp b/source/common/ubidi.cpp
index 3ddb457..6d27827 100644
--- a/source/common/ubidi.cpp
+++ b/source/common/ubidi.cpp
@@ -2047,7 +2047,7 @@
             break;
 
         default:                        /* we should never get here */
-            UPRV_UNREACHABLE;
+            UPRV_UNREACHABLE_EXIT;
         }
     }
     if((addLevel) || (start < start0)) {
@@ -2250,7 +2250,7 @@
                 start2=i;
                 break;
             default:            /* we should never get here */
-                UPRV_UNREACHABLE;
+                UPRV_UNREACHABLE_EXIT;
             }
         }
     }
@@ -2724,7 +2724,7 @@
             break;
         default:
             /* we should never get here */
-            UPRV_UNREACHABLE;
+            UPRV_UNREACHABLE_EXIT;
         }
         /*
          * If there are no external levels specified and there