feat: File attachments (#3031)

* stash

* refactor, working in non-collab + collab editor

* attachment styling

* Avoid crypto require in browser

* AttachmentIcon, handling unknown types

* Do not allow attachment creation for file sizes over limit

* Allow image as file attachment

* Upload placeholder styling

* lint

* Refactor: Do not use placeholder for file attachmentuploads

* Add loading spinner

* fix: Extra paragraphs around attachments on insert

* Bump editor

* fix build error

* Remove attachment placeholder when upload fails

* Remove unused styles

* fix: Attachments on shared pages

* Merge fixes

server/editor/renderToHtml.ts

@@ -1,5 +1,6 @@
 import { PluginSimple } from "markdown-it";
 import createMarkdown from "@shared/editor/lib/markdown/rules";
+import attachmentsRule from "@shared/editor/rules/attachments";
 import breakRule from "@shared/editor/rules/breaks";
 import checkboxRule from "@shared/editor/rules/checkboxes";
 import embedsRule from "@shared/editor/rules/embeds";
@@ -18,6 +19,7 @@ const defaultRules = [
   underlinesRule,
   tablesRule,
   noticesRule,
+  attachmentsRule,
   emojiRule,
 ];