Offchain-worker: Make it possible to disable http support (#10087)

* Offchain-worker: Make it possible to disable http support

If a chain doesn't require http support in its offchain workers, this pr enables them to disable the
http support.

* Switch to bitflags

* Use Capabilities

* Update client/offchain/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Fix test

* Update client/offchain/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

substrate/primitives/core/src/lib.rs

@@ -118,15 +118,13 @@ impl ExecutionContext {
 		use ExecutionContext::*;
 
 		match self {
-			Importing | Syncing | BlockConstruction => offchain::Capabilities::none(),
+			Importing | Syncing | BlockConstruction => offchain::Capabilities::empty(),
 			// Enable keystore, transaction pool and Offchain DB reads by default for offchain
 			// calls.
-			OffchainCall(None) => [
-				offchain::Capability::Keystore,
-				offchain::Capability::OffchainDbRead,
-				offchain::Capability::TransactionPool,
-			][..]
-				.into(),
+			OffchainCall(None) =>
+				offchain::Capabilities::KEYSTORE |
+					offchain::Capabilities::OFFCHAIN_DB_READ |
+					offchain::Capabilities::TRANSACTION_POOL,
 			OffchainCall(Some((_, capabilities))) => *capabilities,
 		}
 	}