Clear file inputs after jobs (#2248)

src/main/resources/templates/merge-pdfs.html

@@ -40,6 +40,9 @@
                 <button type="button" id="sortByDateBtn" class="btn btn-info" th:text="#{merge.sortByDate}"></button>
                 <button type="submit" id="submitBtn" class="btn btn-primary" th:text="#{merge.submit}"></button>
               </div>
+              <div class="mb-3">
+                <button type="button" id="resetFileInputBtn" class="btn btn-danger" th:text="#{reset}">Reset</button>
+              </div>
             </form>
             <span id="pageTranslation" th:text="#{page}" style="display:none;"></span>
             <span id="pagesTranslation" th:text="#{pages}" style="display:none;"></span>