Auto merge of #116156 - oli-obk:opaque_place_unwrap, r=compiler-errors

Only prevent field projections into opaque types, not types containing opaque types

fixes rust-lang/rust#115778

I did not think that original condition through properly... I'll also need to check the similar check around the other `ProjectionKind::OpaqueCast` creation site (this one is in hir, the other one is in mir), but I'll do that change in another PR that doesn't go into a beta backport.

Author: bors