runtime-rs: make Container::new async

Fixes: #6714

Signed-off-by: Zixuan Tan <tanzixuan.me@gmail.com>

src/runtime-rs/crates/runtimes/virt_container/src/container_manager/container.rs

@@ -46,7 +46,7 @@ pub struct Container {
 }
 
 impl Container {
-    pub fn new(
+    pub async fn new(
         pid: u32,
         config: ContainerConfig,
         spec: oci::Spec,

src/runtime-rs/crates/runtimes/virt_container/src/container_manager/manager.rs

@@ -78,6 +78,7 @@ impl ContainerManager for VirtContainerManager {
             self.agent.clone(),
             self.resource_manager.clone(),
         )
+        .await
         .context("new container")?;
 
         // CreateContainer Hooks: