state_machine no_std witness externalities (#6934)

* checkpoint before removing CT from change trie

* before trie backend without tx

* undo

* Started no transaction, but would need using a different root
calculation method, out of the scope of this pr, will roll back.

* Remove NoTransaction.

* partially address review.
dummy stats implementation for no_std.

* Remove ChangeTrieOverlay.

* modified function

* Remove witness_ext

* need noops changes root

* update from cumulus branch

* line break

* remove warning

* line break

* From review: renamings and stats active in no std (except time).

* include cache, exclude change trie cache with individual temporary bad looking
no_std check

* little test

* fuse imports and filter_map prepare_extrinsics_input_inner fold.

* put back ExtInner into Ext, awkward double proto for new function.

* Apply suggestions from code review

* Update primitives/state-machine/Cargo.toml

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

substrate/primitives/externalities/src/lib.rs

@@ -15,6 +15,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#![cfg_attr(not(feature = "std"), no_std)]
+
 //! Substrate externalities abstraction
 //!
 //! The externalities mainly provide access to storage and to registered extensions. Extensions
@@ -23,7 +25,7 @@
 //!
 //! This crate exposes the main [`Externalities`] trait.
 
-use std::any::{Any, TypeId};
+use sp_std::{any::{Any, TypeId}, vec::Vec, boxed::Box};
 
 use sp_storage::{ChildInfo, TrackedStorageKey};