Refactor sr_primitives. (#3214)

* refactor sr_primitives.

* Fix try build error.

* Line-width

* Ui test.

* Final fixes.

* Fix build again.

* bring back ui test.

* Fix unsigned import.

* Another ui fix.

* Also refactor substrate-primitives

* Fix benchmarks.

* Fix doc test.

* fix doc tests

substrate/core/offchain/src/lib.rs

@@ -45,7 +45,7 @@ use primitives::{
 	ExecutionContext,
 	crypto,
 };
-use runtime_primitives::{
+use sr_primitives::{
 	generic::BlockId,
 	traits::{self, ProvideRuntimeApi},
 };