Fix/hide pdf no sheet

[Emilecross]

Description

Fixes # Fix unwanted loading of the pdf-viewer component when it was not needed (no task sheet) Add No Task sheet text alongside the icon for better information

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested using frontend, tutor view

Testing Checklist:

• [x] Tested in latest Chrome
• [x] Tested in latest Safari

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [ ] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have requested a review from @macite and @jakerenzella on the Pull Request

[Emilecross]

Student view no good, clicking on something with a pdf then clicking off gives bad behaviour

[Emilecross]

Student view issues are unrelated to this current change, reopening