[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.
ghstack-source-id: 314913615

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

Author: mariusae

hyperactor_mesh/benches/main.rs

@@ -13,6 +13,7 @@ use criterion::Criterion;
 use criterion::Throughput;
 use criterion::criterion_group;
 use criterion::criterion_main;
+use hyperactor::Proc;
 use hyperactor::channel::ChannelTransport;
 use hyperactor_mesh::ProcMesh;
 use hyperactor_mesh::actor_mesh::ActorMesh;
@@ -51,9 +52,10 @@ fn bench_actor_scaling(c: &mut Criterion) {
                     .await
                     .unwrap();
 
+                let (bootstrap_instance, _) = Proc::local().instance("bench").unwrap();
                 let mut proc_mesh = ProcMesh::allocate(alloc).await.unwrap();
                 let actor_mesh: RootActorMesh<BenchActor> = proc_mesh
-                    .spawn("bench", &(Duration::from_millis(0)))
+                    .spawn(&bootstrap_instance, "bench", &(Duration::from_millis(0)))
                     .await
                     .unwrap();
                 let client = proc_mesh.client();
@@ -149,9 +151,10 @@ fn bench_actor_mesh_message_sizes(c: &mut Criterion) {
                             .await
                             .unwrap();
 
+                        let (bootstrap_instance, _) = Proc::local().instance("bench").unwrap();
                         let mut proc_mesh = ProcMesh::allocate(alloc).await.unwrap();
                         let actor_mesh: RootActorMesh<BenchActor> = proc_mesh
-                            .spawn("bench", &(Duration::from_millis(0)))
+                            .spawn(&bootstrap_instance, "bench", &(Duration::from_millis(0)))
                             .await
                             .unwrap();
 

hyperactor_mesh/examples/dining_philosophers.rs

@@ -20,6 +20,7 @@ use hyperactor::Handler;
 use hyperactor::Instance;
 use hyperactor::Named;
 use hyperactor::PortRef;
+use hyperactor::Proc;
 use hyperactor::Unbind;
 use hyperactor::channel::ChannelTransport;
 use hyperactor_mesh::ProcMesh;
@@ -237,10 +238,12 @@ async fn main() -> Result<ExitCode> {
         })
         .await?;
 
+    let (instance, _) = Proc::local().instance("client").unwrap();
+
     let proc_mesh = ProcMesh::allocate(alloc).await?;
     let params = PhilosopherActorParams { size: group_size };
     let actor_mesh = proc_mesh
-        .spawn::<PhilosopherActor>("philosopher", &params)
+        .spawn::<PhilosopherActor>(&instance, "philosopher", &params)
         .await?;
     let (dining_message_handle, mut dining_message_rx) = proc_mesh.client().open_port();
     actor_mesh