Add keyboard shortcuts for heading styles to CKeditor

[DavidBAsch]

As a content designer adding content using Drupal’s CKEditor.

I would like to be able to use keyboard shortcuts to apply heading styles to content.

So that I can speed up my workflow by removing the need to scroll up to the content bar each time.

Wordpress version of the CMS editor showing its keyboard shortcuts.

@willguv

[markconroy]

I'm moving this to the localgov_core repo as I think if we are going to implement this it should be for all of localgov and not just the base theme (which isn't actually used when editing content).

[willguv]

Content group 23 May doesn't think this is a priority

[willguv]

Content group 20 June - more interest in this "would use if its there"

[stephen-cox]

We're about to move from CKeditor 4 to 5 (#161) so this should wait until that work is done.

[DavidBAsch]

For reference, here's the complete list of shortcuts (just sayin'...).

https://wordpress.org/documentation/article/keyboard-shortcuts-classic-editor/