Investigate and find possible alternatives for underscore-prefixed CKEditor methods

Problem/Motivation

CKEditor may consider removing underscore-prefixed methods in the future, and asked us to audit our usage.

The methods we use are:

• _setHtmlSupportViewAttributes
• _repositionImageContextualBalloon
• _getImageBalloonPositionData
• _LINK_KEYSTROKE
• _ImageStyleUtils

They have since asked us:

• What are the use cases for each of these functions?
• In what scenarios or workflows do they come into play?

This issue exists to answer these questions.

Steps to reproduce

Proposed resolution

Remaining tasks

Investigate each of the methods and describe why we use them.
Look for possible alternatives.

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet