Safe and sane multi-item storage removal (#11490)

* Fix overlay prefix removal result

* Second part of the overlay prefix removal fix.

* Report only items deleted from storage in clear_prefix

* Fix kill_prefix

* Formatting

* Remove unused code

* Fixes

* Fixes

* Introduce clear_prefix host function v3

* Formatting

* Use v2 for now

* Fixes

* Formatting

* Docs

* Child prefix removal should also hide v3 for now

* Fixes

* Fixes

* Formatting

* Fixes

* apply_to_keys_whle takes start_at

* apply_to_keys_whle takes start_at

* apply_to_keys_whle takes start_at

* Cursor API; force limits

* Use unsafe deprecated functions

* Formatting

* Fixes

* Grumbles

* Fixes

* Docs

* Some nitpicks 🙈

* Update primitives/externalities/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Formatting

* Fixes

* cargo fmt

* Fixes

* Update primitives/io/src/lib.rs

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* Formatting

* Fixes

Co-authored-by: Bastian Köcher <info@kchr.de>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

substrate/frame/uniques/src/functions.rs

@@ -110,8 +110,10 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			for (item, details) in Item::<T, I>::drain_prefix(&collection) {
 				Account::<T, I>::remove((&details.owner, &collection, &item));
 			}
+			#[allow(deprecated)]
 			ItemMetadataOf::<T, I>::remove_prefix(&collection, None);
 			CollectionMetadataOf::<T, I>::remove(&collection);
+			#[allow(deprecated)]
 			Attribute::<T, I>::remove_prefix((&collection,), None);
 			CollectionAccount::<T, I>::remove(&collection_details.owner, &collection);
 			T::Currency::unreserve(&collection_details.owner, collection_details.total_deposit);