feat: implement Markdown and HTML page imports (#85)

* page import feature
* make file interceptor common

* replace @tiptap/html
* update tiptap version

* reduce table margin

* update tiptap version

* switch to upstream drag handle lib (fixes table dragging)

* WIP

* Page import module and other fixes

* working page imports

* extract page title from h1 heading

* finalize page imports

* cleanup unused imports

* add menu arrow

apps/server/src/common/helpers/prosemirror/html/generateJSON.ts

@@ -0,0 +1,20 @@
+import { Extensions, getSchema } from '@tiptap/core';
+import { DOMParser, ParseOptions } from '@tiptap/pm/model';
+import { Window, DOMParser as HappyDomParser } from 'happy-dom';
+
+export function generateJSON(
+  html: string,
+  extensions: Extensions,
+  options?: ParseOptions,
+): Record<string, any> {
+  const schema = getSchema(extensions);
+
+  const window = new Window();
+  const dom = new HappyDomParser(window).parseFromString(
+    html,
+    'text/html',
+  ).body;
+
+  // @ts-ignore
+  return DOMParser.fromSchema(schema).parse(dom, options).toJSON();
+}