Make candidate validation timeouts configurable (#4001)

* pvf: make execution timeout configurable

* guide: add timeouts to candidate validation params

* add timeouts to candidate validation messages

* fmt

* port backing to use the backing pvf timeout

* port approval-voting to use the execution timeout

* port dispute participation to use the correct timeout

* fmt

* address grumbles & test failure

polkadot/node/core/pvf/tests/it/main.rs

@@ -20,11 +20,13 @@ use polkadot_node_core_pvf::{
 	start, Config, InvalidCandidate, Metrics, Pvf, ValidationError, ValidationHost,
 };
 use polkadot_parachain::primitives::{BlockData, ValidationParams, ValidationResult};
+use std::time::Duration;
 
 mod adder;
 mod worker_common;
 
 const PUPPET_EXE: &str = env!("CARGO_BIN_EXE_puppet_worker");
+const TEST_EXECUTION_TIMEOUT: Duration = Duration::from_secs(3);
 
 struct TestHost {
 	_cache_dir: tempfile::TempDir,
@@ -64,6 +66,7 @@ impl TestHost {
 			.await
 			.execute_pvf(
 				Pvf::from_code(code.into()),
+				TEST_EXECUTION_TIMEOUT,
 				params.encode(),
 				polkadot_node_core_pvf::Priority::Normal,
 				result_tx,