CLI improvements & fixes (#4812)

These are a few changes I missed during the refactoring.

1. Initialization issue and boilerplate

    Most importantly: part of the `Configuration` initialization was done in `sc_cli::init`. This means the user can not benefit from this initialization boilerplate if they have multiple `Configuration` since `sc_cli::init` can only be called once.

2. Boilerplate for `VersionInfo` and `Configuration`

    I'm also answering to the critic of @bkchr on the initialization using version: https://github.com/paritytech/substrate/pull/4692/files/bea809d4c14a2ede953227ac885e3b3f9771c548#r372047238 This will allow initializing a `Configuration` and provide the version by default.

3. Loading the `chain_spec` explicitly

    In the past it was done automatically but in some cases we want to delay this. I moved the code to `Configuration.load_spec()` so it can be called later on. `chain_spec` can also be written directly to the `Configuration` without using this `load_spec` helper.

4. [deleted]

5. Fixing issue that prevents the user to override the port

    In the refactoring I introduced a bug by mistake that could potentially prevent the CLI user to override the ports if defaults where provided for these ports (only on cumulus).

6. Change task_executor from Box to Arc

    This is useful for cumulus where we have 2 nodes with 2 separate Configuration that need to spawn tasks to the same runtime.

7. Renamed TasksExecutorRequired to TaskExecutor

    For consistency.

This is related to https://github.com/paritytech/cumulus/issues/24

This is the continuation (and hopefully the end of) #4692

substrate/client/service/test/src/lib.rs

@@ -133,7 +133,7 @@ fn node_config<G, E: Clone> (
 	index: usize,
 	spec: &ChainSpec<G, E>,
 	role: Roles,
-	task_executor: Box<dyn Fn(Pin<Box<dyn futures::Future<Output = ()> + Send>>) + Send>,
+	task_executor: Arc<dyn Fn(Pin<Box<dyn futures::Future<Output = ()> + Send>>) + Send + Sync>,
 	key_seed: Option<String>,
 	base_port: u16,
 	root: &TempDir,
@@ -183,10 +183,10 @@ fn node_config<G, E: Clone> (
 			password: None
 		},
 		config_dir: Some(root.clone()),
-		database: DatabaseConfig::Path {
+		database: Some(DatabaseConfig::Path {
 			path: root.join("db"),
 			cache_size: None
-		},
+		}),
 		state_cache_size: 16777216,
 		state_cache_child_ratio: None,
 		pruning: Default::default(),
@@ -256,7 +256,7 @@ impl<G, E, F, L, U> TestNet<G, E, F, L, U> where
 		for (key, authority) in authorities {
 			let task_executor = {
 				let executor = executor.clone();
-				Box::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
+				Arc::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
 			};
 			let node_config = node_config(
 				self.nodes,
@@ -280,7 +280,7 @@ impl<G, E, F, L, U> TestNet<G, E, F, L, U> where
 		for full in full {
 			let task_executor = {
 				let executor = executor.clone();
-				Box::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
+				Arc::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
 			};
 			let node_config = node_config(self.nodes, &self.chain_spec, Roles::FULL, task_executor, None, self.base_port, &temp);
 			let addr = node_config.network.listen_addresses.iter().next().unwrap().clone();
@@ -296,7 +296,7 @@ impl<G, E, F, L, U> TestNet<G, E, F, L, U> where
 		for light in light {
 			let task_executor = {
 				let executor = executor.clone();
-				Box::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
+				Arc::new(move |fut: Pin<Box<dyn futures::Future<Output = ()> + Send>>| executor.spawn(fut.unit_error().compat()))
 			};
 			let node_config = node_config(self.nodes, &self.chain_spec, Roles::LIGHT, task_executor, None, self.base_port, &temp);
 			let addr = node_config.network.listen_addresses.iter().next().unwrap().clone();