Move runtime upgrade to frame-executive (#5197)

* Move runtime upgrade to `frame-executive`

Instead of storing the runtime upgraded in the space of `frame-system`,
this moves it to `frame-executive`. We also start storing the
`spec_version` and `impl_version` the last runtime upgrade was applied.

This scheme has multiple advantages:
- We don't need to make sure that runtime upgrade was set.
- This will work in the future when we want to test a runtime upgrade,
because the `on_runtime_upgrade` will be executed automatically when the
runtime changes.

* Move `LAST_RUNTIME_UPGRADE` key to `frame-executive`

* Add some more documentation

* Make sure `spec_version` always increases between runtime upgrades

* Fix test

* Upgrade `parity-multiaddr` to fix compilation

* Also check if the `spec_name` changed

* Remove `RuntimeUpgraded` storage entry

* Don't run on genesis

substrate/client/rpc/src/state/tests.rs

@@ -402,7 +402,7 @@ fn should_return_runtime_version() {
 	let api = new_full(client.clone(), Subscriptions::new(Arc::new(core.executor())));
 
 	let result = "{\"specName\":\"test\",\"implName\":\"parity-test\",\"authoringVersion\":1,\
-		\"specVersion\":1,\"implVersion\":2,\"apis\":[[\"0xdf6acb689907609b\",2],\
+		\"specVersion\":2,\"implVersion\":2,\"apis\":[[\"0xdf6acb689907609b\",2],\
 		[\"0x37e397fc7c91f5e4\",1],[\"0xd2bc9897eed08f15\",1],[\"0x40fe3ad401f8959a\",4],\
 		[\"0xc6e9a76309f39b09\",1],[\"0xdd718d5cc53262d4\",1],[\"0xcbca25e39f142387\",1],\
 		[\"0xf78b278be53f454c\",2],[\"0xab3c0572291feb8b\",1],[\"0xbc9d89904f5b923f\",1]]}";