Test all abilities to select an existing Mauro element to insert as a link in editors

[pjmonks]

The Markdown/HTML editors allow the user to select through the UI an existing Mauro item to reference as a hyperlink in description fields:

All variations of link insertion should be tested to ensure that:

1. All work correctly without any bugs
2. Whether the UX is acceptable

Note: this is prioritised for the NHS Data Dictionary to ensure that the UX Is up to scratch.

Wait until the following issues have been resolved:

• Include toolbar options in the markdown editor #573
• Create internal links when editing long text more easily with a shortcut #418