feat(import/markdown): maintain consistency with CKEditor for images

src/services/import/markdown.spec.ts

@@ -102,4 +102,10 @@ second line 2</code></pre><ul><li>Hello</li><li>world</li></ul><ol><li>Hello</li
         expect(markdownService.renderToHtml(input, "Title")).toStrictEqual(expected);
     });
 
+    it("imports images with same outcome as if inserted from CKEditor", () => {
+        const input = "![](api/attachments/YbkR3wt2zMcA/image/image)";
+        const expected = `<p><img src="api/attachments/YbkR3wt2zMcA/image/image"></p>`;
+        expect(markdownService.renderToHtml(input, "Title")).toStrictEqual(expected);
+    });
+
 });

src/services/import/markdown.ts

@@ -34,6 +34,11 @@ class CustomMarkdownRenderer extends Renderer {
         return super.listitem(item).trimEnd();
     }
 
+    image(token: Tokens.Image): string {
+        return super.image(token)
+            .replace(` alt=""`, "");
+    }
+
     blockquote({ tokens }: Tokens.Blockquote): string {
         const body = renderer.parser.parse(tokens);
 
@@ -72,6 +77,9 @@ function renderToHtml(content: string, title: string) {
     html = importUtils.handleH1(html, title);
     html = htmlSanitizer.sanitize(html);
 
+    // Remove slash for self-closing tags to match CKEditor's approach.
+    html = html.replace(/<(\w+)([^>]*)\s+\/>/g, "<$1$2>");
+
     return html;
 }