ch-remote: Make snapshot and restore config arguments required

The snapshot and restore subcommands in ch-remote had optional
snapshot_config and restore_config arguments, but the implementation was
unconditionally unwrapping them.

This change marks these arguments as required to handle the missing
argument validation and report a proper error message instead of letting
the application panic.

Signed-off-by: Andrei Vagin <avagin@google.com>

cloud-hypervisor/src/bin/ch-remote.rs

@@ -1127,6 +1127,7 @@ fn get_cli_commands_sorted() -> Box<[Command]> {
             .arg(
                 Arg::new("restore_config")
                     .index(1)
+                    .required(true)
                     .help(RestoreConfig::SYNTAX),
             ),
         Command::new("resume").about("Resume the VM"),
@@ -1144,6 +1145,7 @@ fn get_cli_commands_sorted() -> Box<[Command]> {
             .arg(
                 Arg::new("snapshot_config")
                     .index(1)
+                    .required(true)
                     .help("<destination_url>"),
             ),
     ]