[MM-16389] Add icon_emoji parameter to webhooks (#11586)

[MM-16389] Add icon_emoji field to posts from incoming webhooks

To be used to substitute the profile picture on posts.

app/import_functions.go

@@ -1287,7 +1287,7 @@ func (a *App) ImportEmoji(data *EmojiImportData, dryRun bool) *model.AppError {
 
 	var emoji *model.Emoji
 
-	emoji, appError := a.Srv.Store.Emoji().GetByName(*data.Name)
+	emoji, appError := a.Srv.Store.Emoji().GetByName(*data.Name, true)
 	if appError != nil && appError.StatusCode != http.StatusNotFound {
 		return appError
 	}