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/state-machine/src/error.rs

@@ -17,7 +17,7 @@
 
 /// State Machine Errors
 
-use std::fmt;
+use sp_std::fmt;
 
 /// State Machine Error bound.
 ///
@@ -34,7 +34,7 @@ impl<T: 'static + fmt::Debug + fmt::Display + Send> Error for T {}
 #[derive(Debug, Eq, PartialEq)]
 pub enum ExecutionError {
 	/// Backend error.
-	Backend(String),
+	Backend(crate::DefaultError),
 	/// The entry `:code` doesn't exist in storage so there's no way we can execute anything.
 	CodeEntryDoesNotExist,
 	/// Backend is incompatible with execution proof generation process.