[Shortcuts] Add an icon hash attribute in shortcuts.xml.

This information is needed to figure out whether an WebAPK update
is required.

Bug: 1045588
Change-Id: I42485a8490b5ee639a433c5466ce54380270421a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2030971Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737292}

chrome/android/webapk/shell_apk/current_version/current_version.gni

@@ -12,4 +12,4 @@
 # //chrome/android/webapk/shell_apk:webapk is changed. This includes
 # Java files, Android resource files and AndroidManifest.xml. Does not affect
 # Chrome.apk
-current_shell_apk_version = 120
+current_shell_apk_version = 121

chrome/android/webapk/shell_apk/res/xml/shortcuts.xml

@@ -4,6 +4,7 @@
   <shortcut
     android:shortcutId='shortcut_1'
     android:icon='@drawable/shortcut_1_icon'
+    iconHash='{{{icon_hash}}}'
     android:shortcutShortLabel='@string/shortcut_1_short_name'
     android:shortcutLongLabel='@string/shortcut_1_name'>
       <intent
@@ -18,6 +19,7 @@
   <shortcut
     android:shortcutId='shortcut_2'
     android:icon='@drawable/shortcut_2_icon'
+    iconHash='{{{icon_hash}}}'
     android:shortcutShortLabel='@string/shortcut_2_short_name'
     android:shortcutLongLabel='@string/shortcut_2_name'>
       <intent
@@ -32,6 +34,7 @@
   <shortcut
     android:shortcutId='shortcut_3'
     android:icon='@drawable/shortcut_3_icon'
+    iconHash='{{{icon_hash}}}'
     android:shortcutShortLabel='@string/shortcut_3_short_name'
     android:shortcutLongLabel='@string/shortcut_3_name'>
       <intent
@@ -46,6 +49,7 @@
   <shortcut
     android:shortcutId='shortcut_4'
     android:icon='@drawable/shortcut_4_icon'
+    iconHash='{{{icon_hash}}}'
     android:shortcutShortLabel='@string/shortcut_4_short_name'
     android:shortcutLongLabel='@string/shortcut_4_name'>
       <intent