Offchain execution extensions (#4145)

* Pass Extensions instead of individual objects.

* Move TransactionPool to a separate ExternalitiesExtension.

* Fix compilation.?

* Clean up.

* Refactor testing utilities.

* Add docs, fix tests.

* Fix doctest.

* Fix formatting and add some logs.

* Add some docs.

* Remove unused files.

substrate/test/utils/client/src/lib.rs

@@ -20,7 +20,8 @@
 
 pub mod client_ext;
 
-pub use client::{ExecutionStrategies, blockchain, self};
+pub use client::{blockchain, self};
+pub use client_api::execution_extensions::{ExecutionStrategies, ExecutionExtensions};
 pub use client_db::{Backend, self};
 pub use client_ext::ClientExt;
 pub use consensus;
@@ -194,7 +195,10 @@ impl<Executor, Backend, G: GenesisInit> TestClientBuilder<Executor, Backend, G>
 			executor,
 			storage,
 			Default::default(),
-			self.execution_strategies,
+			ExecutionExtensions::new(
+				self.execution_strategies,
+				self.keystore.clone(),
+			)
 		).expect("Creates new client");
 
 		let longest_chain = client::LongestChain::new(self.backend);
@@ -210,7 +214,7 @@ impl<E, Backend, G: GenesisInit> TestClientBuilder<
 > {
 	/// Build the test client with the given native executor.
 	pub fn build_with_native_executor<Block, RuntimeApi, I>(
-		mut self,
+		self,
 		executor: I,
 	) -> (
 		client::Client<
@@ -229,7 +233,7 @@ impl<E, Backend, G: GenesisInit> TestClientBuilder<
 		let executor = executor.into().unwrap_or_else(||
 			NativeExecutor::new(WasmExecutionMethod::Interpreted, None)
 		);
-		let executor = LocalCallExecutor::new(self.backend.clone(), executor, self.keystore.take());
+		let executor = LocalCallExecutor::new(self.backend.clone(), executor);
 
 		self.build_with_executor(executor)
 	}