Auto merge of #119821 - oli-obk:reveal_all_const_evals, r=lcnr

Always use RevealAll for const eval queries

implements what is described in rust-lang/rust#116803 (comment)

Using `UserFacing` for const eval does not make sense anymore, unless we significantly change things like avoiding revealing opaque types.

New tests are copied from rust-lang/rust#101478

Author: bors