rustdoc: hide inherent impls with private impl items

[lcnr]

cc #137576. Rustdoc currently shows inherent impl items even if all impl items are private. This affects BTreeMap:

rust/library/alloc/src/collections/btree/map.rs

Lines 292 to 315 in ad27045

	/// Internal functionality for `BTreeSet`.
	impl<K, A: Allocator + Clone> BTreeMap<K, SetValZST, A> {
	pub(super) fn replace(&mut self, key: K) -> Option<K>
	where
	K: Ord,
	{
	let (map, dormant_map) = DormantMutRef::new(self);
	let root_node =
	map.root.get_or_insert_with(|| Root::new((*map.alloc).clone())).borrow_mut();
	match root_node.search_tree::<K>(&key) {
	Found(mut kv) => Some(mem::replace(kv.key_mut(), key)),
	GoDown(handle) => {
	VacantEntry {
	key,
	handle: Some(handle),
	dormant_map,
	alloc: (*map.alloc).clone(),
	_marker: PhantomData,
	}
	.insert(SetValZST);
	None
	}
	}
	}

I feel like the proper fix for this issue is for rustdoc to not show internal inherent impls even if the impl has a doc comment.