Fix #8745 - GND is now -XSafe compatible.

As discussed in the ticket, after the landing of #8773, GND is now
-XSafe compatible.

This fixes the test fallout as well. In particular SafeLang07 was
removed following in the steps of SafeLang06, since it no longer failed
from GND, but failed due to roles and was thus invalid.

The other tests were tweaked to use TemplateHaskell instead of GND in
order to trigger safety warnings.

Signed-off-by: Austin Seipp <austin@well-typed.com>