文本文档加入缓存，安全修复XSS，美化404、500报错等，新增SVG格式预览，ofd优化印章渲染兼容性 (#413)

1、文本文档加入缓存
2、安全修复XSS(跨站脚本攻击)
3、美化404、500报错等
5、新增 SVG格式预览
5、ofd优化印章渲染兼容性

Co-authored-by: gaoxiongzaq <admin@cxcp.com>

server/src/main/java/cn/keking/service/FilePreview.java

@@ -17,6 +17,7 @@ public interface FilePreview {
     String PICTURE_FILE_PREVIEW_PAGE = "picture";
     String TIFF_FILE_PREVIEW_PAGE = "tiff";
     String OFD_FILE_PREVIEW_PAGE = "ofd";
+    String SVG_FILE_PREVIEW_PAGE = "svg";
     String OFFICE_PICTURE_FILE_PREVIEW_PAGE = "officePicture";
     String TXT_FILE_PREVIEW_PAGE = "txt";
     String CODE_FILE_PREVIEW_PAGE = "code";