DEV: no need to pass down skip_notifications for expanding mentions

This refactoring simplifies `ChatNotifier` a bit. I want to drop that argument for `expand_direct_mentions` too, but that needs a bit deeper refactoring, so it's better to do it separately.

plugins/chat/assets/stylesheets/common/base-common.scss

@@ -384,7 +384,6 @@ $float-height: 530px;
 
       .d-icon {
         color: var(--secondary);
-        margin-left: 1px; // "fixes" the 1px svg shift
       }
     }
 

plugins/chat/assets/stylesheets/common/chat-message-separator.scss

@@ -56,9 +56,7 @@
     }
 
     .chat-message-separator__text-container {
-      align-items: center;
-      display: flex;
-      height: 40px;
+      padding-top: 7px;
       position: sticky;
       top: -1px;
 
@@ -100,7 +98,11 @@
 
       .chat-message-separator__line {
         border-top: 1px solid var(--secondary-high);
+        left: 0;
         margin: 0 0 -1px;
+        position: relative;
+        right: 0;
+        top: -1px;
       }
     }
   }

plugins/chat/lib/chat/notifier.rb

@@ -130,9 +130,11 @@ module Chat
         already_covered_ids = []
 
         expand_direct_mentions(to_notify, already_covered_ids, skip_notifications)
-        expand_group_mentions(to_notify, already_covered_ids, skip_notifications)
-        expand_here_mention(to_notify, already_covered_ids, skip_notifications)
-        expand_global_mention(to_notify, already_covered_ids, skip_notifications)
+        if !skip_notifications
+          expand_group_mentions(to_notify, already_covered_ids)
+          expand_here_mention(to_notify, already_covered_ids)
+          expand_global_mention(to_notify, already_covered_ids)
+        end
 
         filter_users_ignoring_or_muting_creator(to_notify, already_covered_ids)
 
@@ -140,10 +142,10 @@ module Chat
       end
     end
 
-    def expand_global_mention(to_notify, already_covered_ids, skip)
+    def expand_global_mention(to_notify, already_covered_ids)
       has_all_mention = @mentions.has_global_mention
 
-      if has_all_mention && @chat_channel.allow_channel_wide_mentions && !skip
+      if has_all_mention && @chat_channel.allow_channel_wide_mentions
         to_notify[:global_mentions] = @mentions
           .global_mentions
           .not_suspended
@@ -157,10 +159,10 @@ module Chat
       end
     end
 
-    def expand_here_mention(to_notify, already_covered_ids, skip)
+    def expand_here_mention(to_notify, already_covered_ids)
       has_here_mention = @mentions.has_here_mention
 
-      if has_here_mention && @chat_channel.allow_channel_wide_mentions && !skip
+      if has_here_mention && @chat_channel.allow_channel_wide_mentions
         to_notify[:here_mentions] = @mentions
           .here_mentions
           .not_suspended
@@ -212,8 +214,8 @@ module Chat
       already_covered_ids.concat(to_notify[:direct_mentions])
     end
 
-    def expand_group_mentions(to_notify, already_covered_ids, skip)
-      return [] if skip || @mentions.visible_groups.empty?
+    def expand_group_mentions(to_notify, already_covered_ids)
+      return if @mentions.visible_groups.empty?
 
       reached_by_group =
         @mentions