[hyperactor] mesh: v0 shims for v1 meshes

Pull Request resolved: #1453

In this change, we implement:

```
From<v1::ProcMeshRef> for ProcMesh
```

and

```
From<v1::ActorMeshRef<A>> for RootActorMesh<A>
```

This will allow us to temporarily use v1 instances through a v0 API, while we transition the usage sites.

Differential Revision: [D84081478](https://our.internmc.facebook.com/intern/diff/D84081478/)

**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D84081478/)!
ghstack-source-id: 314616752

Author: mariusae

hyperactor_mesh/src/actor_mesh.rs

@@ -199,11 +199,13 @@ mod tests {
             })
             .await
             .unwrap();
+        let instance = crate::v1::testing::instance().await;
 
         let proc_mesh = ProcMesh::allocate(alloc).await.unwrap();
 
         let handle = hyperactor::simnet::simnet_handle().unwrap();
-        let actor_mesh: RootActorMesh<TestActor> = proc_mesh.spawn("echo", &()).await.unwrap();
+        let actor_mesh: RootActorMesh<TestActor> =
+            proc_mesh.spawn(&instance, "echo", &()).await.unwrap();
         let actors = actor_mesh.iter_actor_refs().collect::<Vec<_>>();
         assert_eq!(
             handle.sample_latency(

hyperactor_mesh/src/alloc/sim.rs

@@ -830,9 +830,9 @@ mod tests {
         let params = TestActorParams {
             forward_port: tx.bind(),
         };
-        let actor_mesh = proc_mesh
-            .clone()
-            .spawn::<TestActor>(dest_actor_name, &params)
+        let instance = crate::v1::testing::instance().await;
+        let actor_mesh = Arc::clone(&proc_mesh)
+            .spawn::<TestActor>(&instance, dest_actor_name, &params)
             .await
             .unwrap();
 
@@ -904,7 +904,7 @@ mod tests {
     ) {
         // Reply from each dest actor. The replies should be received by client.
         {
-            for (dest_actor, (reply_to1, reply_to2)) in ranks.iter().zip(reply_tos.iter()) {
+            for (dest_actor, (reply_to1, reply_to2)) in ranks().iter().zip(reply_tos.iter()) {
                 let rank = dest_actor.actor_id().rank() as u64;
                 reply_to1.send(instance, rank).unwrap();
                 let my_reply = MyReply {
@@ -926,7 +926,7 @@ mod tests {
         {
             let n = 100;
             let mut expected2: HashMap<usize, Vec<MyReply>> = hashmap! {};
-            for (dest_actor, (_reply_to1, reply_to2)) in ranks.iter().zip(reply_tos.iter()) {
+            for (dest_actor, (_reply_to1, reply_to2)) in ranks().iter().zip(reply_tos.iter()) {
                 let rank = dest_actor.actor_id().rank();
                 let mut sent2 = vec![];
                 for i in 0..n {
@@ -946,7 +946,7 @@ mod tests {
 
             let mut received2: HashMap<usize, Vec<MyReply>> = hashmap! {};
 
-            for _ in 0..(n * ranks.len()) {
+            for _ in 0..(n * ranks().len()) {
                 let my_reply = reply2_rx.recv().await.unwrap();
                 received2
                     .entry(my_reply.sender.rank())