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/core/client/src/runtime_api.rs

@@ -69,7 +69,21 @@ pub trait ApiExt<Block: BlockT> {
 	fn has_api<A: RuntimeApiInfo + ?Sized>(
 		&self,
 		at: &BlockId<Block>
-	) -> error::Result<bool> where Self: Sized;
+	) -> error::Result<bool> where Self: Sized {
+		self.runtime_version_at(at).map(|v| v.has_api::<A>())
+	}
+
+	/// Check if the given api is implemented and the version passes a predicate.
+	fn has_api_with<A: RuntimeApiInfo + ?Sized, P: Fn(u32) -> bool>(
+		&self,
+		at: &BlockId<Block>,
+		pred: P,
+	) -> error::Result<bool> where Self: Sized {
+		self.runtime_version_at(at).map(|v| v.has_api_with::<A, _>(pred))
+	}
+
+	/// Returns the runtime version at the given block id.
+	fn runtime_version_at(&self, at: &BlockId<Block>) -> error::Result<RuntimeVersion>;
 }
 
 /// Something that can call into the runtime at a given block.