Backport for GHC 9.0

Backports to %9.0.1.

• !4006 (closed)
• !3718 (closed)
• !3707 (closed)
• !3829 (closed)
• !3826 (closed)
• !3846 (closed)
• !3893 (merged)
• !3924 (closed)
• !3946 (closed)
• !3921 (closed)
• !3856 (closed)
• !4003 (closed)
• !3988 (closed)
• !4046 (closed)
• !3610 (closed)
• !3902 (closed)