Do existence check on navigator.clipboard

[rtibbles]

Summary

Description of the change(s) you made

• Adds existence checks everywhere that navigator.clipboard is referenced
• Hides copy buttons and prevents the clipboard being used

Manual verification steps performed

1. Checked that token copying still works in admin and non-admin

References

Fixes #3637

[marcellamaki]

Looks good to me. Code makes sense, checked to ensure token copying still works, and also did a check with clipboardAvailable() manually set to false for copying from the token model and it is prevented.