chore: remove unused `loadingHistoryMessagesInProgress` property

`loadingHistoryMessagesInProgress` was moved to content module but the
property was never removed from the messages module view

see: fc24f16525

src/app/modules/main/chat_section/chat_content/messages/view.nim

@@ -10,7 +10,6 @@ QtObject:
       model: Model
       modelVariant: QVariant
       initialMessagesLoaded: bool
-      loadingHistoryMessagesInProgress: bool
       messageSearchOngoing: bool
 
   proc delete*(self: View) =
@@ -111,21 +110,6 @@ QtObject:
     self.initialMessagesLoaded = true
     self.initialMessagesLoadedChanged()
 
-  proc loadingHistoryMessagesInProgressChanged*(self: View) {.signal.}
-
-  proc getLoadingHistoryMessagesInProgress*(self: View): bool {.slot.} =
-    return self.loadingHistoryMessagesInProgress
-
-  QtProperty[bool] loadingHistoryMessagesInProgress:
-    read = getLoadingHistoryMessagesInProgress
-    notify = loadingHistoryMessagesInProgressChanged
-
-  proc setLoadingHistoryMessagesInProgress*(self: View, value: bool) = # this is not a slot
-    if (value == self.loadingHistoryMessagesInProgress):
-      return
-    self.loadingHistoryMessagesInProgress = value
-    self.loadingHistoryMessagesInProgressChanged()
-
   proc loadMoreMessages*(self: View) {.slot.} =
     self.delegate.loadMoreMessages()