LMS-2498 Prevent Users insert text after a quoted structure

Request Summary

When creating a quoted structure, you can use the tab key to navigate outside the quoted structure and enter additional spaces or text, this can result in the PDF rendering incorrectly. Either prevent users entering text here or open the appropriate dialogue box to add the following text.

Background

In https://lawmaker.atlassian.net/browse/LMS-2443 this ‘novice’ user may have used this method to add the following text, which then created an additional space in the XML causing the full stop to render below the quoted structure rather than at the end of the last line of the QS. There may also be another can when user did this to enter a paragraph. Preventing users from doing this should reduce validation errors needed to be resolved by the service team.