Add keyboard shortcut to CKeditor

[rivernews]

Items:

• [ ] Save: ctrl + S
• [x] Heading, other formating, etc.

Ref

• Ckeditor-React repo
• Our custom Ckeditor build repo
• Ckeditor
  • The keydown event
  • How to start writing Ckeditor plugin
  • How to add plugin into editor

[rivernews]

Adding Save Shortcut

• We now have ckeditor emitting event onKeydown
• How to control the form submit behavior? We want ctrl+S to trigger a submit-like effect.
  • It should be at form level, instead of field level, so that we can trigger the submit function.
  • ... // TODO

We end up using ckeditor's keystroke handler to capture this specific "ctrl + s" shortcut, and then expose as a React prop, and in turn, in Formik fire submitForm upon event.

Referring to this SO post, inspired by it.