Rollup merge of #104317 - RalfJung:ctfe-error-reporting, r=oli-obk

cleanup and dedupe CTFE and Miri error reporting

It looks like most of the time, this error raised from const_prop_lint is just redundant -- it duplicates the error reported when evaluating the const-eval query. This lets us make `ConstEvalErr` private to the const_eval module which I think is a good step.

The Miri change mostly replaces a `match` by `if let`, and dedupes the "this error is impossible in Miri" checks.

r? ``@oli-obk``
Fixes https://github.com/rust-lang/rust/issues/75461

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -189,7 +189,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             all_consts_ok = false;
             match err {
                 // errored or at least linted
-                ErrorHandled::Reported(_) | ErrorHandled::Linted => {}
+                ErrorHandled::Reported(_) => {}
                 ErrorHandled::TooGeneric => {
                     span_bug!(const_.span, "codegen encountered polymorphic constant: {:?}", err)
                 }