Fix killing simctl process and caller

In case when ios-sim-portable is used as a library, in a CLI for example, sending Ctrl + C should kill the CLI process and its related resources.
However, in case the code is currently executing `xcrun simctl` command, sending Ctrl + C does not kill the CLI process. There are two reasons for this:
* we use Node.js's `child_process.spawnSync` method to call `xcrun simctl` commands
* simctl handles the killing signals in its own manner

When the executable passed to spawnSync method has its own logic for handling Signals for termination, Node.js process does not receive the Signals. That's why, the spawned process just exits and CLI's code continues.
However, the returned result has a signal property showing the signal used to kill the process.
In order to send the same signal to CLI, just check if the `signal` property is set and send it to the current Node.js process as well.

Author: rosen-vladimirov

lib/simctl.ts

@@ -32,15 +32,15 @@ export class Simctl implements ISimctl {
 	}
 
 	public install(deviceId: string, applicationPath: string): void {
-		return this.simctlExec("install", [deviceId, applicationPath]);
+		this.simctlExec("install", [deviceId, applicationPath]);
 	}
 
 	public uninstall(deviceId: string, appIdentifier: string, opts?: any): void {
-		return this.simctlExec("uninstall", [deviceId, appIdentifier], opts);
+		this.simctlExec("uninstall", [deviceId, appIdentifier], opts);
 	}
 
 	public notifyPost(deviceId: string, notification: string): void {
-		return this.simctlExec("notify_post", [deviceId, notification]);
+		this.simctlExec("notify_post", [deviceId, notification]);
 	}
 
 	public getAppContainer(deviceId: string, appIdentifier: string): string {
@@ -120,11 +120,20 @@ export class Simctl implements ISimctl {
 		return devices;
 	}
 
-	private simctlExec(command: string, args: string[], opts?: any): any {
-		let result = childProcess.spawnSync("xcrun", ["simctl", command].concat(args), opts);
-		if(result && result.stdout) {
-			return result.stdout.toString().trim();
+	private simctlExec(command: string, args: string[], opts?: any): string {
+		const result = childProcess.spawnSync("xcrun", ["simctl", command].concat(args), opts);
+		if (result) {
+			if (result.signal) {
+				// In some cases, sending Ctrl + C (SIGINT) is handled by the simctl itself and spawnSync finishes, but the SIGINT does not stop current process.
+				// In order to ensure the same signal is sent to the caller (CLI for example), send the signal manually:
+				process.send(result.signal);
+			}
+
+			if (result.stdout) {
+				return result.stdout.toString().trim();
+			}
 		}
+
 		return '';
 	}
 }