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

shared/i18n/locales/en_US/translation.json

@@ -194,6 +194,7 @@
   "Center large": "Center large",
   "Italic": "Italic",
   "Sorry, that link won’t work for this embed type": "Sorry, that link won’t work for this embed type",
+  "File attachment": "File attachment",
   "Find or create a doc": "Find or create a doc",
   "Big heading": "Big heading",
   "Medium heading": "Medium heading",
@@ -201,7 +202,7 @@
   "Heading": "Heading",
   "Divider": "Divider",
   "Image": "Image",
-  "Sorry, an error occurred uploading the image": "Sorry, an error occurred uploading the image",
+  "Sorry, an error occurred uploading the file": "Sorry, an error occurred uploading the file",
   "Write a caption": "Write a caption",
   "Info": "Info",
   "Info notice": "Info notice",