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/impl/SvgFilePreviewImpl.java

@@ -0,0 +1,27 @@
+package cn.keking.service.impl;
+
+import cn.keking.model.FileAttribute;
+import cn.keking.service.FilePreview;
+import org.springframework.stereotype.Service;
+import org.springframework.ui.Model;
+
+/**
+ * svg 图片文件处理
+ * @author kl (http://kailing.pub)
+ * @since 2021/2/8
+ */
+@Service
+public class SvgFilePreviewImpl implements FilePreview {
+
+    private final PictureFilePreviewImpl pictureFilePreview;
+
+    public SvgFilePreviewImpl(PictureFilePreviewImpl pictureFilePreview) {
+        this.pictureFilePreview = pictureFilePreview;
+    }
+
+    @Override
+    public String filePreviewHandle(String url, Model model, FileAttribute fileAttribute) {
+        pictureFilePreview.filePreviewHandle(url,model,fileAttribute);
+        return SVG_FILE_PREVIEW_PAGE;
+    }
+}