chore(proto): Add ping request.

Signed-off-by: Bo-Yi Wu <[email protected]>

client/client.go

@@ -0,0 +1,11 @@
+package client
+
+import (
+	"context"
+)
+
+// A Client manages communication with the runner.
+type Client interface {
+	// Ping sends a ping message to the server to test connectivity.
+	Ping(ctx context.Context, machine string) error
+}