Auto merge of #102233 - petrochenkov:effvis, r=jackh726

privacy: Rename "accessibility levels" to "effective visibilities"

And a couple of other naming and comment tweaks.

Related to https://github.com/rust-lang/rust/issues/48054

For `enum Level` I initially used naming `enum EffectiveVisibilityLevel`, but it was too long and inconvenient because it's used pretty often.
So I shortened it to just `Level`, if it needs to be used from some context where this name would be ambiguous, then it can be imported with renaming like `use rustc_middle::privacy::Level as EffVisLevel` or something.

compiler/rustc_middle/src/ty/mod.rs

@@ -17,7 +17,7 @@ pub use self::IntVarValue::*;
 pub use self::Variance::*;
 use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
 use crate::metadata::ModChild;
-use crate::middle::privacy::AccessLevels;
+use crate::middle::privacy::EffectiveVisibilities;
 use crate::mir::{Body, GeneratorLayout};
 use crate::traits::{self, Reveal};
 use crate::ty;
@@ -160,7 +160,7 @@ pub struct ResolverGlobalCtxt {
     pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
     /// Reference span for definitions.
     pub source_span: IndexVec<LocalDefId, Span>,
-    pub access_levels: AccessLevels,
+    pub effective_visibilities: EffectiveVisibilities,
     pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
     pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
     pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,