Add a new host function for reporting fatal errors; make WASM backtraces readable when printing out errors (#10741)

* Add a new host function for reporting fatal errors

* Fix one of the wasmtime executor tests

* Have `#[runtime_interface(wasm_only)]` actually mean WASM-only, and not no_std-only

* Print out errors through `Display` instead of `Debug`

* Switch one more trait to require `Error` for its error instead of only `Debug`

* Align to review comments

substrate/client/authority-discovery/src/error.rs

@@ -38,7 +38,7 @@ pub enum Error {
 	#[error("Failed to hash the authority id to be used as a dht key.")]
 	HashingAuthorityId(#[from] libp2p::core::multiaddr::multihash::Error),
 
-	#[error("Failed calling into the Substrate runtime.")]
+	#[error("Failed calling into the Substrate runtime: {0}")]
 	CallingRuntime(#[from] sp_blockchain::Error),
 
 	#[error("Received a dht record with a key that does not match any in-flight awaited keys.")]