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/consensus/aura/src/import_queue.rs

@@ -205,7 +205,7 @@ where
 		let hash = block.header.hash();
 		let parent_hash = *block.header.parent_hash();
 		let authorities = authorities(self.client.as_ref(), &BlockId::Hash(parent_hash))
-			.map_err(|e| format!("Could not fetch authorities at {:?}: {:?}", parent_hash, e))?;
+			.map_err(|e| format!("Could not fetch authorities at {:?}: {}", parent_hash, e))?;
 
 		let create_inherent_data_providers = self
 			.create_inherent_data_providers
@@ -249,7 +249,7 @@ where
 							&BlockId::Hash(parent_hash),
 							|v| v >= 2,
 						)
-						.map_err(|e| format!("{:?}", e))?
+						.map_err(|e| e.to_string())?
 					{
 						self.check_inherents(
 							new_block.clone(),