Add input handling

frontend/src/scripts/commands/command-generator.ts

@@ -0,0 +1,14 @@
+import { CommandReceiver } from './command-receiver';
+import { Command } from './command';
+
+export class CommandGenerator {
+  private subscribers: Array<CommandReceiver> = [];
+
+  public subscribe(subscriber: CommandReceiver): void {
+    this.subscribers.push(subscriber);
+  }
+
+  protected sendCommand(command: Command): void {
+    this.subscribers.forEach((s) => s.sendCommand(command));
+  }
+}