fix: stop dompurify from breaking draw.io diagrams (#7888)

Newer versions of dompurify strip <foreignobject> tags if not explicitly
allowed. See https://github.com/cure53/DOMPurify/issues/1040

Fixes #7744

client/components/editor/editor-asciidoc.vue

@@ -228,7 +228,8 @@ export default {
       })
 
       this.previewHTML = DOMPurify.sanitize($.html(), {
-        ADD_TAGS: ['foreignObject']
+        ADD_TAGS: ['foreignObject'],
+        HTML_INTEGRATION_POINTS: { foreignobject: true }
       })
     },
     /**

client/components/editor/editor-markdown.vue

@@ -454,7 +454,8 @@ export default {
       // this.$store.set('editor/content', newContent)
       this.processMarkers(this.cm.firstLine(), this.cm.lastLine())
       this.previewHTML = DOMPurify.sanitize(md.render(newContent), {
-        ADD_TAGS: ['foreignObject']
+        ADD_TAGS: ['foreignObject'],
+        HTML_INTEGRATION_POINTS: { foreignobject: true }
       })
       this.$nextTick(() => {
         tabsetHelper.format()

server/modules/rendering/html-security/renderer.js

@@ -34,7 +34,8 @@ module.exports = {
 
       input = DOMPurify.sanitize(input, {
         ADD_ATTR: allowedAttrs,
-        ADD_TAGS: allowedTags
+        ADD_TAGS: allowedTags,
+        HTML_INTEGRATION_POINTS: { foreignobject: true }
       })
     }
     return input