add NodeFeatures field to HostConfiguration and runtime API (#2177)

Adds a `NodeFeatures` bitfield value to the runtime `HostConfiguration`,
with the purpose of coordinating the enabling of node-side features,
such as: https://github.com/paritytech/polkadot-sdk/issues/628 and
https://github.com/paritytech/polkadot-sdk/issues/598.
These are features that require all validators enable them at the same
time, assuming all/most nodes have upgraded their node versions.

This PR doesn't add any feature yet. These are coming in future PRs.

Also adds a runtime API for querying the state of the client features
and an extrinsic for setting/unsetting a feature by its index in the bitfield.

Note: originally part of:
https://github.com/paritytech/polkadot-sdk/pull/1644, but posted as
standalone to be reused by other PRs until the initial PR is merged

cumulus/client/relay-chain-minimal-node/src/blockchain_rpc_client.rs

@@ -24,6 +24,7 @@ use polkadot_overseer::RuntimeApiSubsystemClient;
 use polkadot_primitives::{
 	async_backing::{AsyncBackingParams, BackingState},
 	slashing,
+	vstaging::NodeFeatures,
 };
 use sc_authority_discovery::{AuthorityDiscovery, Error as AuthorityDiscoveryError};
 use sp_api::{ApiError, RuntimeApiInfo};
@@ -364,6 +365,10 @@ impl RuntimeApiSubsystemClient for BlockChainRpcClient {
 	) -> Result<Option<BackingState>, ApiError> {
 		Ok(self.rpc_client.parachain_host_para_backing_state(at, para_id).await?)
 	}
+
+	async fn node_features(&self, at: Hash) -> Result<NodeFeatures, ApiError> {
+		Ok(self.rpc_client.parachain_host_node_features(at).await?)
+	}
 }
 
 #[async_trait::async_trait]