Implement the Runtime API subsystem (#1494)

* type defaults for ParachainHost

* add ValidationCode message

* implement core loop of runtime API subsystem

* subsystem trait implementation for runtime API subsystem

* implement a mock runtime API

* some tests that ensure requests are forwarded to runtime API correctly

* fix dependency grumbles

* improve RuntimeApiError API

Cargo.toml

@@ -43,9 +43,10 @@ members = [
 	"service",
 	"validation",
 
+	"node/core/av-store",
 	"node/core/bitfield-signing",
 	"node/core/proposer",
-	"node/core/av-store",
+	"node/core/runtime-api",
 	"node/network/bridge",
 	"node/network/pov-distribution",
 	"node/network/statement-distribution",

node/core/runtime-api/Cargo.toml

@@ -6,17 +6,15 @@ edition = "2018"
 
 [dependencies]
 futures = "0.3.5"
-log = "0.4.8"
 sp-api = { git = "https://github.com/paritytech/substrate", branch = "master" }
-sc-client-api = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-blockchain = { git = "https://github.com/paritytech/substrate", branch = "master" }
-primitives = { package = "sp-core", git = "https://github.com/paritytech/substrate", branch = "master" }
 
 polkadot-primitives = { path = "../../../primitives" }
 polkadot-node-primitives = { path = "../../primitives" }
 polkadot-subsystem = { package = "polkadot-node-subsystem", path = "../../subsystem" }
 
 [dev-dependencies]
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
 futures = { version = "0.3.5", features = ["thread-pool"] }
-subsystem-test = { package = "polkadot-subsystem-test-helpers", path = "../../test-helpers/subsystem" }
+polkadot-subsystem = { package = "polkadot-node-subsystem", path = "../../subsystem", features = ["test-helpers"] }
 assert_matches = "1.3.0"