icons: Add message_checked icon, from Figma

Figma doesn't specify this icon explicitly. Based on discussions in PR zulip#1274
(zulip#1274 (comment)),
we chose this icon for consistency with the "Mark as read" option on web.

reference: https://www.figma.com/design/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=3512-7&t=iwirdCVutQls9R0A-4

Author: chimnayajith

assets/icons/ZulipIcons.ttf

@@ -102,44 +102,47 @@ abstract final class ZulipIcons {
   /// The Zulip custom icon "menu".
   static const IconData menu = IconData(0xf11a, fontFamily: "Zulip Icons");
 
+  /// The Zulip custom icon "message_checked".
+  static const IconData message_checked = IconData(0xf11b, fontFamily: "Zulip Icons");
+
   /// The Zulip custom icon "message_feed".
-  static const IconData message_feed = IconData(0xf11b, fontFamily: "Zulip Icons");
+  static const IconData message_feed = IconData(0xf11c, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "mute".
-  static const IconData mute = IconData(0xf11c, fontFamily: "Zulip Icons");
+  static const IconData mute = IconData(0xf11d, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "read_receipts".
-  static const IconData read_receipts = IconData(0xf11d, fontFamily: "Zulip Icons");
+  static const IconData read_receipts = IconData(0xf11e, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "send".
-  static const IconData send = IconData(0xf11e, fontFamily: "Zulip Icons");
+  static const IconData send = IconData(0xf11f, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "share".
-  static const IconData share = IconData(0xf11f, fontFamily: "Zulip Icons");
+  static const IconData share = IconData(0xf120, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "share_ios".
-  static const IconData share_ios = IconData(0xf120, fontFamily: "Zulip Icons");
+  static const IconData share_ios = IconData(0xf121, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "smile".
-  static const IconData smile = IconData(0xf121, fontFamily: "Zulip Icons");
+  static const IconData smile = IconData(0xf122, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "star".
-  static const IconData star = IconData(0xf122, fontFamily: "Zulip Icons");
+  static const IconData star = IconData(0xf123, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "star_filled".
-  static const IconData star_filled = IconData(0xf123, fontFamily: "Zulip Icons");
+  static const IconData star_filled = IconData(0xf124, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "three_person".
-  static const IconData three_person = IconData(0xf124, fontFamily: "Zulip Icons");
+  static const IconData three_person = IconData(0xf125, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "topic".
-  static const IconData topic = IconData(0xf125, fontFamily: "Zulip Icons");
+  static const IconData topic = IconData(0xf126, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "unmute".
-  static const IconData unmute = IconData(0xf126, fontFamily: "Zulip Icons");
+  static const IconData unmute = IconData(0xf127, fontFamily: "Zulip Icons");
 
   /// The Zulip custom icon "user".
-  static const IconData user = IconData(0xf127, fontFamily: "Zulip Icons");
+  static const IconData user = IconData(0xf128, fontFamily: "Zulip Icons");
 
   // END GENERATED ICON DATA
 }

assets/icons/message_checked.svg

@@ -50,10 +50,10 @@ packages:
     dependency: transitive
     description:
       name: async
-      sha256: d2872f9c19731c2e5f10444b14686eb7cc85c76274bd6c16e1816bff9a3bab63
+      sha256: "758e6d74e971c3e5aceb4110bfd6698efc7f501675bcfe0c775459a8140750eb"
       url: "https://pub.dev"
     source: hosted
-    version: "2.12.0"
+    version: "2.13.0"
   boolean_selector:
     dependency: transitive
     description:
@@ -291,10 +291,10 @@ packages:
     dependency: "direct dev"
     description:
       name: fake_async
-      sha256: "6a95e56b2449df2273fd8c45a662d6947ce1ebb7aafe80e550a3f68297f3cacc"
+      sha256: "5368f224a74523e8d2e7399ea1638b37aecfca824a3cc4dfdf77bf1fa905ac44"
       url: "https://pub.dev"
     source: hosted
-    version: "1.3.2"
+    version: "1.3.3"
   ffi:
     dependency: transitive
     description:
@@ -607,10 +607,10 @@ packages:
     dependency: "direct main"
     description:
       name: intl
-      sha256: d6f56758b7d3014a48af9701c085700aac781a92a87a62b1333b46d8879661cf
+      sha256: "3df61194eb431efc39c4ceba583b95633a403f46c9fd341e550ce0bfa50e9aa5"
       url: "https://pub.dev"
     source: hosted
-    version: "0.19.0"
+    version: "0.20.2"
   io:
     dependency: transitive
     description:
@@ -647,10 +647,10 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: c35baad643ba394b40aac41080300150a4f08fd0fd6a10378f8f7c6bc161acec
+      sha256: "6bb818ecbdffe216e81182c2f0714a2e62b593f4a4f13098713ff1685dfb6ab0"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.8"
+    version: "10.0.9"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
@@ -1244,10 +1244,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "0968250880a6c5fe7edc067ed0a13d4bae1577fe2771dcf3010d52c4a9d3ca14"
+      sha256: ddfa8d30d89985b96407efce8acbdd124701f96741f2d981ca860662f1c0dc02
       url: "https://pub.dev"
     source: hosted
-    version: "14.3.1"
+    version: "15.0.0"
   wakelock_plus:
     dependency: "direct main"
     description:
@@ -1300,10 +1300,10 @@ packages:
     dependency: transitive
     description:
       name: webdriver
-      sha256: "3d773670966f02a646319410766d3b5e1037efb7f07cc68f844d5e06cd4d61c8"
+      sha256: "2f3a14ca026957870cfd9c635b83507e0e51d8091568e90129fbf805aba7cade"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.4"
+    version: "3.1.0"
   webkit_inspection_protocol:
     dependency: transitive
     description: