This is the same as PR #78306, but unused_doc_comments is modified to explicitly ignore statement items (which preserves the current behavior).

This shouldn't have any user-visible effects, so it can be landed without lang team discussion.

When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. #[allow]) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an unused_attributes for
#[inline], since the sibiling #[allow(unused_attributes)] suppressed
the warning.

trait Foo {
    #[allow(unused_attributes)] #[inline] fn first();
    #[inline] #[allow(unused_attributes)] fn second();
}

However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside StmtKind
(e.g. Item).

Currently, this is difficult to observe due to another issue - the
HasAttrs impl for StmtKind ignores attributes for StmtKind::Item.
As a result, the unused_doc_comments lint will never see attributes on
item statements.

This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:

• The HasAttr impl for StmtKind now returns attributes for
  StmtKind::Item, treating it just like every other StmtKind
  variant. The only place relying on the old behavior was macro
  which has been updated to explicitly ignore attributes on item
  statements. This allows the unused_doc_comments lint to fire for
  item statements.
• The early and late lint visitors now activate lint attributes when
  invoking the callback for Stmt. This ensures that a lint
  attribute (e.g. #[allow(unused_doc_comments)]) can be applied to
  sibiling attributes on an item statement.

For now, the unused_doc_comments lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306