PVF: Refactor workers into separate crates, remove host dependency (#7253)

* PVF: Refactor workers into separate crates, remove host dependency

* Fix compile error

* Remove some leftover code

* Fix compile errors

* Update Cargo.lock

* Remove worker main.rs files

I accidentally copied these from the other PR. This PR isn't intended to
introduce standalone workers yet.

* Address review comments

* cargo fmt

* Update a couple of comments

* Update log targets

polkadot/node/core/pvf/src/host.rs

@@ -22,16 +22,19 @@
 
 use crate::{
 	artifacts::{ArtifactId, ArtifactPathId, ArtifactState, Artifacts},
-	error::PrepareError,
 	execute::{self, PendingExecutionRequest},
 	metrics::Metrics,
-	prepare, PrepareResult, Priority, PvfPrepData, ValidationError, LOG_TARGET,
+	prepare, Priority, ValidationError, LOG_TARGET,
 };
 use always_assert::never;
 use futures::{
 	channel::{mpsc, oneshot},
 	Future, FutureExt, SinkExt, StreamExt,
 };
+use polkadot_node_core_pvf_common::{
+	error::{PrepareError, PrepareResult},
+	pvf::PvfPrepData,
+};
 use polkadot_parachain::primitives::ValidationResult;
 use std::{
 	collections::HashMap,
@@ -423,7 +426,7 @@ async fn handle_precheck_pvf(
 	pvf: PvfPrepData,
 	result_sender: PrepareResultSender,
 ) -> Result<(), Fatal> {
-	let artifact_id = pvf.as_artifact_id();
+	let artifact_id = ArtifactId::from_pvf_prep_data(&pvf);
 
 	if let Some(state) = artifacts.artifact_state_mut(&artifact_id) {
 		match state {
@@ -467,7 +470,7 @@ async fn handle_execute_pvf(
 	inputs: ExecutePvfInputs,
 ) -> Result<(), Fatal> {
 	let ExecutePvfInputs { pvf, exec_timeout, params, priority, result_tx } = inputs;
-	let artifact_id = pvf.as_artifact_id();
+	let artifact_id = ArtifactId::from_pvf_prep_data(&pvf);
 	let executor_params = (*pvf.executor_params()).clone();
 
 	if let Some(state) = artifacts.artifact_state_mut(&artifact_id) {
@@ -590,7 +593,7 @@ async fn handle_heads_up(
 	let now = SystemTime::now();
 
 	for active_pvf in active_pvfs {
-		let artifact_id = active_pvf.as_artifact_id();
+		let artifact_id = ArtifactId::from_pvf_prep_data(&active_pvf);
 		if let Some(state) = artifacts.artifact_state_mut(&artifact_id) {
 			match state {
 				ArtifactState::Prepared { last_time_needed, .. } => {
@@ -854,9 +857,10 @@ fn pulse_every(interval: std::time::Duration) -> impl futures::Stream<Item = ()>
 #[cfg(test)]
 pub(crate) mod tests {
 	use super::*;
-	use crate::{prepare::PrepareStats, InvalidCandidate, PrepareError};
+	use crate::InvalidCandidate;
 	use assert_matches::assert_matches;
 	use futures::future::BoxFuture;
+	use polkadot_node_core_pvf_common::{error::PrepareError, prepare::PrepareStats};
 
 	const TEST_EXECUTION_TIMEOUT: Duration = Duration::from_secs(3);
 	pub(crate) const TEST_PREPARATION_TIMEOUT: Duration = Duration::from_secs(30);
@@ -877,7 +881,7 @@ pub(crate) mod tests {
 
 	/// Creates a new PVF which artifact id can be uniquely identified by the given number.
 	fn artifact_id(descriminator: u32) -> ArtifactId {
-		PvfPrepData::from_discriminator(descriminator).as_artifact_id()
+		ArtifactId::from_pvf_prep_data(&PvfPrepData::from_discriminator(descriminator))
 	}
 
 	fn artifact_path(descriminator: u32) -> PathBuf {