Add support for inline-only text editing

[rungta]

Add support for CKEditor’s Inline Root editor mode to allow configuring a CKEditor field to restrict itself to inline-only editing options (like Bold, Italic, Link) and disable all block-level operations (paras, lists, headings, etc)

Useful for instances when authors need control over the phrasing content of titles, labels, and headings that are currently captured as plain text fields.

(This should be possible simply by upgrading the bundled CKEditor to >= v48.1.0.)