♻️ Refactor exportation and duplicate mechanism

Previously the file processing was implemented 3 times using similar
approaches bug each own with its own bugs. This PR unifies the
loging to a single implementation used by the 3 operations.

backend/resources/app/templates/debug.tmpl

@@ -145,17 +145,6 @@ Debug Main Page
           </small>
         </div>
 
-        <div class="row">
-          <label>Ignore index errors?</label>
-          <input type="checkbox" name="ignore-index-errors" checked/>
-          <br />
-          <small>
-            Do not break on index lookup errors (remap operation).
-            Useful when importing a broken file that has broken
-            relations or missing pieces.
-          </small>
-        </div>
-
         <div class="row">
           <input type="submit" name="upload" value="Upload" />
         </div>