Auto merge of #87739 - Aaron1011:remove-used-attrs, r=wesleywiser

Remove `Session.used_attrs` and move logic to `CheckAttrVisitor`

Instead of updating global state to mark attributes as used,
we now explicitly emit a warning when an attribute is used in
an unsupported position. As a side effect, we are to emit more
detailed warning messages (instead of just a generic "unused" message).

`Session.check_name` is removed, since its only purpose was to mark
the attribute as used. All of the callers are modified to use
`Attribute.has_name`

Additionally, `AttributeType::AssumedUsed` is removed - an 'assumed
used' attribute is implemented by simply not performing any checks
in `CheckAttrVisitor` for a particular attribute.

We no longer emit unused attribute warnings for the `#[rustc_dummy]`
attribute - it's an internal attribute used for tests, so it doesn't
mark sense to treat it as 'unused'.

With this commit, a large source of global untracked state is removed.

compiler/rustc_privacy/src/lib.rs

@@ -885,9 +885,7 @@ impl Visitor<'tcx> for EmbargoVisitor<'tcx> {
     fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
         // Non-opaque macros cannot make other items more accessible than they already are.
         let attrs = self.tcx.hir().attrs(md.hir_id());
-        if attr::find_transparency(&self.tcx.sess, &attrs, md.ast.macro_rules).0
-            != Transparency::Opaque
-        {
+        if attr::find_transparency(&attrs, md.ast.macro_rules).0 != Transparency::Opaque {
             // `#[macro_export]`-ed `macro_rules!` are `Public` since they
             // ignore their containing path to always appear at the crate root.
             if md.ast.macro_rules {