break sp-api dependency cycle (#4352)

* move benches into tests, ignore non-passing doctests

* Rename sr-api folder

* Move test-primitives to primitives, use that for sp-api doctests

substrate/primitives/api/test/tests/ui/adding_self_parameter.rs

@@ -0,0 +1,7 @@
+sp_api::decl_runtime_apis! {
+	pub trait Api {
+		fn test(&self);
+	}
+}
+
+fn main() {}