Edit link description, title, and URL separately in the content editor

Problem to solve

Markdown supports creating links with a description, title, and URL. Creating a link in the content editor is easy, but manipulating that link afterward can be a little tricky. There is no direct support for setting a link title (for accessibility reasons) without switching over to the raw Markdown.

Proposal

Inserting or editing a link should prompt you to provide a URL, description (default to the URL), and a title (default empty, optional).

Availability and Testing

Provided the functionality has lower level test coverage, no changes to E2E suite required, however, we should ensure the happy path test content_editor_spec still passes in the MR.