Make API backwards compatible with CC (#1697)

* Rework how a runtime api calls into the runtime

Now we generate a default implementation for each api call that calls
a generated method `method_runtime_api_impl`. This newly generated
method is the one that will be implemented by the `impl_runtime_apis`
macro in the runtime for the client side.

* Support `changed_in` to change runtime api function signatures

* Update documentation

* Fixes tests

* Implement checking the api version with a predicate

* Make the implementation backwards compatible with CC

* Update wasm files after merge

* Check for wasm runtime differences by building master and current branch

* Update spec_version and wasm files

* Fixes

* Revert my changes

* Remove `patch.crates-io` from test-runtime

substrate/node/runtime/src/lib.rs

@@ -66,8 +66,8 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 20,
-	impl_version: 20,
+	spec_version: 21,
+	impl_version: 21,
 	apis: RUNTIME_API_VERSIONS,
 };