FIX: improves draft for channels (#21724)

This commit attempts to correctly change draft when the channel changes. It moves responsibility to the composer instead of the channel.

A new service `chatDraftsManager` is being introduced here to allow finer control and pave the way for future thread draft support.

These changes also now allow an editing message to be stored as a draft.

plugins/chat/spec/system/page_objects/chat/components/composer.rb

@@ -12,6 +12,10 @@ module PageObjects
           @context = context
         end
 
+        def message_details
+          @message_details ||= PageObjects::Components::Chat::ComposerMessageDetails.new(context)
+        end
+
         def input
           find(context).find(SELECTOR).find(".chat-composer__input")
         end
@@ -31,6 +35,10 @@ module PageObjects
         def open_emoji_picker
           find(context).find(SELECTOR).find(".chat-composer-button__btn.emoji").click
         end
+
+        def editing_message?(message)
+          value == message.message && message_details.editing_message?(message)
+        end
       end
     end
   end

plugins/chat/spec/system/page_objects/chat/components/composer_message_details.rb

@@ -12,13 +12,19 @@ module PageObjects
           @context = context
         end
 
-        def has_message?(message)
-          find(context).find(SELECTOR + "[data-id=\"#{message.id}\"]")
+        def has_message?(message, action: nil)
+          data_attributes = "[data-id=\"#{message.id}\"]"
+          data_attributes << "[data-action=\"#{action}\"]" if action
+          find(context).find(SELECTOR + data_attributes)
         end
 
         def has_no_message?
           find(context).has_no_css?(SELECTOR)
         end
+
+        def editing_message?(message)
+          has_message?(message, action: :edit)
+        end
       end
     end
   end