Manual roll of ICU (flutter/engine#31132)

* [licenses] Updates ICU license regexp and URL

New file in the ICU library use the https scheme for the URL
instead of prior http to declare the license, leading to
the 'unmatched potential copyright' message.

This change removes the issue.

* [icu] Upgrades the ICU library version in use

This change brings in ICU 70.1 which is the latest and greatest of ICU releases.
It sync up with the latest ICU milestone in use in Chromium.

Issue: #flutter/97412

DEPS

@@ -155,7 +155,7 @@ deps = {
    # Chromium-style dependencies.
 
   'src/third_party/icu':
-   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '2b50fa94b07b601293d7c1f791e853bba8ffbb84',
+   Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '2e0f2989441ec2f55abec30f48e89981dbac2c34',
 
   'src/third_party/khronos':
    Var('chromium_git') + '/chromium/src/third_party/khronos.git' + '@' + '7122230e90547962e0f0c627f62eeed3c701f275',

engine/src/flutter/ci/licenses_golden/tool_signature

@@ -1,2 +1,2 @@
-Signature: c42608d945a7c27e30c484ea93636956
+Signature: fd70aa1b20bfff1d7147a26138a14a9f
 

engine/src/flutter/tools/licenses/lib/licenses.dart

@@ -307,6 +307,7 @@ abstract class License implements Comparable<License> {
         body = system.File('data/mit').readAsStringSync();
         type = LicenseType.mit;
         break;
+      case 'https://www.unicode.org/copyright.html':
       case 'http://www.unicode.org/copyright.html':
         body = system.File('data/unicode').readAsStringSync();
         type = LicenseType.icu;

engine/src/flutter/tools/licenses/lib/patterns.dart

@@ -1156,7 +1156,7 @@ final List<MultipleVersionedLicenseReferencePattern> csReferencesByUrl = <Multip
     pattern: RegExp(
       kIndent +
       r'(?:©|Copyright (©|\(C\))) 20.. and later: Unicode, Inc. and others.[ *]*\n'
-      r'^\1\2License & terms of use: (http://www.unicode.org/copyright.html)',
+      r'^\1\2License & terms of use: (https?://www.unicode.org/copyright.html)',
       multiLine: true,
       caseSensitive: false,
     )