Replace Vec<u8> with [u8; 32] for contract storage key (#2184)

* Replace Vec<u8> with [u8; 32] for contract storage key

* Read storage keys from sandbox memory into fixed size buffer

* Increment `impl_version`

substrate/node/runtime/src/lib.rs

@@ -60,7 +60,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
 	spec_version: 57,
-	impl_version: 57,
+	impl_version: 58,
 	apis: RUNTIME_API_VERSIONS,
 };